Uplink sounding reference signals configuration and transmission

ABSTRACT

A wireless transmit/receive unit (WTRU) is configured to receive a WTRU-specific configuration of WTRU-specific sounding reference signal (SRS) subframes for performing SRS transmissions. The WTRU is configured to receive a trigger in a subframe to transmit a first SRS. The WTRU is configured to select a first subframe. The WTRU is configured to determine that a maximum power would be exceeded in a symbol in the selected first subframe. The WTRU is configured to, on a condition that transmission of at least one other SRS would at least partially overlap in the symbol in the selected first subframe, scale transmission powers of the first SRS and the at least one other SRS equally to comply with the maximum power. The WTRU is configured to transmit, in accordance with the scaled transmission powers, the first SRS in the selected subframe and the at least one other SRS.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/684,407, filed Aug. 23, 2017, which is a continuation of U.S. patentapplication Ser. No. 13/078,531, filed Apr. 1, 2011, which issued onAug. 29, 2017 as U.S. Pat. No. 9,749,968, which claims the benefit ofU.S. Provisional Application No. 61/320,576 filed Apr. 2, 2010; U.S.Provisional Application No. 61/330,158 filed Apr. 30, 2010; and U.S.Provisional Application No. 61/388,992 filed Oct. 1, 2010, the contentsof which are hereby incorporated by reference herein.

FIELD OF THE INVENTION

This application is related to wireless communications.

BACKGROUND

For Long Term Evolution (LTE) Release 8 (R8) and Release 9 (R9),wireless transmit/receive units (WTRUs) transmit sounding referencesignals (SRS) periodically based on a schedule and transmissionparameters that are provided semi-statically to the WTRU by the evolvedNode B (eNB) via a combination of broadcast and radio resource control(RRC) dedicated signaling. Cell-specific SRS configurations define thesubframes in which SRS are permitted to be transmitted by WTRUs for agiven cell. WTRU-specific SRS configurations define the subframes andthe transmission parameters to be used by a specific WTRU. Theseconfigurations are provided to the WTRU via RRC signaling. In itsWTRU-specific subframes, a WTRU may transmit SRS in the last symbolacross the entire frequency band of interest with a single SRStransmission, or across part of the band with hopping in the frequencydomain in such a way that a sequence of SRS transmissions jointly coversthe frequency band of interest. The cyclic shift and the transmissioncomb are configurable by higher layer signaling. In LTE R8/9, a maximumof eight different cyclic shifts are possible and two differenttransmission combs. The transmission comb is a frequency multiplexingscheme; each comb includes every other subcarrier over the band ofinterest. In contrast to the multiplexing of SRS transmission by meansof different cyclic shifts, frequency multiplexing of SRS transmissionsdoes not require the transmissions to cover identical frequency bands.

LTE-Advanced (LTE-A), (referring to at least LTE Release 10 (LTE R10)),may provide aperiodic SRS transmissions to reduce the number ofunnecessary SRS transmissions and to alleviate the potential problem ofnot having enough SRS resources to support the added SRS transmissionsneeded for WTRUs with multiple antennas. In particular, dynamicaperiodic SRS may be provided but signaling and other aspects have notbeen identified. For aperiodic SRS transmission, a WTRU may need to knowin what subframe(s) to transmit the SRS and with what parameters. Inaddition to the LTE R8 parameters, such as cyclic shift and transmissioncomb, the WTRU may also need to know on which component carrier (CC) andwith which antenna(s) to transmit. In order for the WTRU to know when totransmit the aperiodic SRS, several triggering mechanisms may be usedincluding uplink (UL) grants, downlink (DL) grants, RRC signaling,medium access control (MAC) control elements and group-based orindividual-based physical downlink control channels (PDCCH). Withrespect to the use of UL or DL grants, activation bit(s) may be used aswell as having the grant alone be the trigger but no particulars havebeen provided. Mechanisms for configuring the SRS transmissionresources/parameters may include semi-static configuration via RRCsignaling as well as PDCCH based configuration being included with thetrigger but again no particulars have been provided.

SUMMARY

Methods and apparatus for uplink sounding reference signals (SRS)configuration and transmission. The methods include receivingconfiguration of wireless transmit/receive unit (WTRU)-specific SRSsubframes for transmitting SRS and upon receipt of a trigger from a basestation, transmitting the SRS for a given number of antennas. The SRStransmissions may occur in each subframe of a duration of WTRU-specificSRS subframes that start a number of WTRU-specific SRS subframes after atriggering subframe. For multiple SRS transmissions from multipleantennas, cyclic shift multiplexing and different transmission combs maybe used. The cyclic shift for an antenna may be determined from a cyclicshift reference value, where the cyclic shift determined for eachantenna provides a maximum distance or even distribution between cyclicshifts for the antennas transmitting SRS in a same WTRU-specificsubframe. SRS transmissions from multiple antennas in the WTRU-specificsubframe may be done in parallel and the number of antennas may be lessthan the number of antennas available on the WTRU. Methods for handlingcollisions between SRS, physical uplink shared channel, and physicaluplink control channel are also presented.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is a flowchart of an example sounding reference signals (SRS)configuration and transmission;

FIG. 3 is a flowchart of an example procedure for determining maximalcyclic shift separation;

FIG. 4 is a diagram of sounding reference signals (SRS) transmissionsubframes, cyclic shift (CS) and transmission comb (TC) for N_(Ant)^(SRS)=2 and N_(subframes) ^(SRS)=1;

FIG. 5 is a diagram of SRS transmission subframes, CS and TC for N_(Ant)^(SRS)=2 and N_(subframes) ^(SRS)=2;

FIG. 6 is a diagram of SRS transmission subframes, CS and TC for N_(Ant)^(SRS)=4 and N_(subframes) ^(SRS)=1;

FIG. 7 is a diagram of SRS transmission subframes, CS and TC for N_(Ant)^(SRS)=4 and N_(subframes) ^(SRS)=2;

FIG. 8 is a diagram of SRS transmission subframes, CS and TC for N_(Ant)^(SRS)=4 and N_(subframes) ^(SRS)=4;

FIG. 9 is a flowchart of an example procedure to handle conflictsbetween SRS and physical uplink shared channel (PUSCH) transmissions;and

FIG. 10 is a flowchart of an example procedure to handle conflictsbetween SRS and physical uplink control channel (PUCCH) transmissions.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, a relay node, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, a relay node, and the like. While the base stations 114a, 114 b are each depicted as a single element, it will be appreciatedthat the base stations 114 a, 114 b may include any number ofinterconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 106, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 106.

The RAN 104 may include eNode-Bs 140 a, 140 b, 140 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 140 a, 140 b, 140c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 140 a, 140 b, 140 c may implement MIMO technology. Thus,the eNode-B 140 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 140 a, 140 b, 140 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1C, theeNode-Bs 140 a, 140 b, 140 c may communicate with one another over an X2interface.

The core network 106 shown in FIG. 1C may include a mobility managementgateway (MME) 142, a serving gateway 144, and a packet data network(PDN) gateway 146. While each of the foregoing elements are depicted aspart of the core network 106, it will be appreciated that any one ofthese elements may be owned and/or operated by an entity other than thecore network operator.

The MME 142 may be connected to each of the eNode-Bs 142 a, 142 b, 142 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 142 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the eNode Bs 140 a,140 b, 140 c in the RAN 104 via the S1 interface. The serving gateway144 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 144 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 144 may also be connected to the PDN gateway 146,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 108. In addition, the corenetwork 106 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

In LTE Release 8 and Release 9 (LTE R8/9), cell-specific soundingreference signals (SRS) configurations define the subframes in which SRSare permitted to be transmitted by WTRUs for a given cell. WTRU-specificSRS configurations define the subframes and the transmission parametersto be used by a specific WTRU. These configurations are provided to theWTRU via radio resource control (RRC) signaling. The cell-specificsubframe configuration is provided to the WTRU in the form of aconfiguration number with possible integer values of 0, 1, 2, . . . 15.The number, srs-SubframeConfig, is provided by higher layers. Eachconfiguration number corresponds to a configuration period in subframes,T_(SFC) and a set of one or more cell-specific transmission offsets insubframes Δ_(SFC) for the SRS transmission. The configuration periodT_(SFC) is selected from the set {1, 2, 5, 10} ms or subframes forfrequency division duplex (FDD) and from the set {5, 10} ms or subframesfor time division duplexing (TDD). The transmission offset Δ_(SFC)identifies the subframe(s) in each configuration period that may be usedin the cell for SRS. The relationship between srs-SubframeConfig,T_(SFC) and Δ_(SFC) is provided in Table 1 for FDD and Table 2 for TDD.SRS subframes are the subframes satisfying └n_(s)/2┘modT_(SFC)∈Δ_(SFC)where n_(s) is the slot number within the frame. For frame structuretype 2, SRS may be transmitted only in configured uplink (UL) subframesor an uplink pilot timeslot (UpPTS).

TABLE 1 Configuration Transmission offset srs- Period T_(SFC) Δ_(SFC)SubframeConfig Binary (subframes) (subframes) 0 0000 1 {0} 1 0001 2 {0}2 0010 2 {1} 3 0011 5 {0} 4 0100 5 {1} 5 0101 5 {2} 6 0110 5 {3} 7 01115 {0, 1} 8 1000 5 {2, 3} 9 1001 10 {0} 10 1010 10 {1} 11 1011 10 {2} 121100 10 {3} 13 1101 10 {0, 1, 2, 3, 4, 6, 8} 14 1110 10 {0, 1, 2, 3, 4,5, 6, 8} 15 1111 reserved reserved

TABLE 2 Configuration Transmission srs- Period T_(SRC) offset Δ_(SFC)SubframeConfig Binary (subframes) (subframes) 0 0000 5 {1} 1 0001 5 {1,2} 2 0010 5 {1, 3} 3 0011 5 {1, 4} 4 0100 5 {1, 2, 3} 5 0101 5 {1, 2, 4}6 0110 5 {1, 3, 4} 7 0111 5 {1, 2, 3, 4} 8 1000 10 {1, 2, 6} 9 1001 10{1, 3, 6} 10 1010 10 {1, 6, 7} 11 1011 10 {1, 2, 6, 8} 12 1100 10 {1, 3,6, 9} 13 1101 10 {1, 4, 6, 7} 14 1110 reserved reserved 15 1111 reservedreserved

The following SRS parameters are WTRU-specific semi-staticallyconfigurable by higher layers: Transmission comb k_(TC); startingphysical resource block assignment n_(RRC); duration: single orindefinite (until disabled); SRS configuration index, srs-ConfigIndex orI_(SRS) which corresponds to an SRS periodicity T_(SRS) and an SRSsubframe offset T_(offset); SRS bandwidth B_(SRS); frequency hoppingbandwidth, b_(hop); and cyclic shift n_(SRS) ^(cs).

The correspondence between the WTRU-specific SRS configuration index andSRS periodicity T_(SRS) and SRS subframe offset T_(offset) is defined inTable 3 and Table 4 below, for FDD and TDD, respectively. Theperiodicity T_(SRS) of the SRS transmission is selected from the set {2,5 (5 is FDD only), 10, 20, 40, 80, 160, 320} ms or subframes. For theSRS periodicity T_(SRS) of 2 ms in TDD, two SRS resources may beconfigured in a half frame containing UL subframe(s).

SRS transmission instances for TDD with T_(SRS)>2 and for FDD are thesubframes satisfying (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0, wheren_(f) is the system frame number; for FDD k_(SRS)={0, 1, . . . , 9} isthe subframe index within the frame, and for TDD k_(SRS) is defined inTable 5 below. The SRS transmission instances for TDD with T_(SRS)=2 arethe subframes satisfying (k_(SRS)−T_(offset))mod 5=0.

TABLE 3 SRS Configuration SRS Periodicity SRS Subframe Index I_(SRS)T_(SRS) (ms) Offset T_(offset) 0-1 2 I_(SRS) 2-6 5 I_(SRS) − 2   7-16 10I_(SRS) − 7  17-36 20 I_(SRS) − 17 37-76 40 I_(SRS) − 37  77-156 80I_(SRS) − 77 157-316 160  I_(SRS) − 157 317-636 320  I_(SRS) − 317 637-1023 reserved reserved

TABLE 4 SRS Configuration SRS Periodicity SRS Subframe Index I_(SPS)T_(SRS) (ms) Offset T_(offset) 0 2 0, 1 1 2 0, 2 2 2 1, 2 3 2 0, 3 4 21, 3 5 2 0, 4 6 2 1, 4 7 2 2, 3 8 2 2, 4 9 2 3, 4 10-14 5 I_(SRS) − 1015-24 10 I_(SRS) − 15 25-44 20 I_(SRS) − 25 45-84 40 I_(SRS) − 45 85-164 80 I_(SRS) − 85 165-324 160 I_(SRS) − 165 325-644 320 I_(SRS) −325  645-1023 reserved reserved

TABLE 5 subframe index n 6 1 2nd 1st symbol 2nd symbol 1st symbol symbolof 0 of UpPTS of UpPTS 2 3 4 5 of UpPTS UpPTS 7 8 9 k_(SRS) in case 0 12 3 4 5 6 7 8 9 UpPTS length of 2 symbols k_(SRS) in case UpPTS length 12 3 4 6 7 8 9 of 1 symbol

The cell-specific subframe configuration may be signaled (to all WTRUs)via broadcast system information. What is actually signaled issrs-SubframeConfig which provides the period T_(SFC) and thetransmission offset(s) Δ_(SFC) within the period. The WTRU-specificsubframe configuration is signaled to each individual WTRU via dedicatedsignaling. What is actually signaled is the SRS Configuration IndexI_(SRS) which provides the WTRU-specific period T_(SRS) and the set ofone or two (only for TDD with I_(SRS)=2) WTRU-specific subframe offsetsT_(offset).

In LTE R8, a WTRU may support SRS transmission from only one antennaport in an allowed SRS subframe and may be targeted towards operation inmacro-cells where few WTRUs are assumed to be deployed with large signalto interference and noise ratio (SINR) to benefit from wideband SRStransmission. As such, SRS overhead may not be a significant part of thetotal uplink (UL) overhead. In LTE R8, (for WTRUs with a single ULtransmit antenna), no more than 1/12^(th) of the UL capacity, (in theextended cyclic prefix (CP) case) may be lost due to SRS transmissionoverhead. For most configurations, the loss is less than 1/12^(th).

However, in LTE-Advanced (LTE-A), (referring to at least LTE Release 10(LTE R10)), UL multiple input multiple output (MIMO) with up to fourantennas, the SRS overhead may increase by a factor of 4. Furthermore,in LTE-A with non-contiguous resource allocation (RA) within onecomponent carrier (CC), carrier aggregation (CA) with multiple CCs, ULcoordinated multiple transmit (CoMP), and expanded deployment inhot-spot/indoor environments, the SRS overhead may increasesignificantly.

SRS capacity may be defined as the maximum number of sounding referencesignals that may be transmitted over a predefined sounding bandwidth andchannel coherence time. Following LTE R8/9 rules for assigning soundingreference signals to multiple antennas without considering additionalsounding resources, SRS capacity may not be enough to fulfill LTE R10requirements in any of the narrowband and wideband sounding cases.

Described herein are methods and apparatus for UL SRS configuration andtransmission. Methods and procedures are provided so that WTRUs knowwhen to transmit SRSs for each antenna port and with whattime/frequency/code resource assignments. In particular, methods toassign resources for UL SRS transmission for WTRUs with multiple ULantenna ports, in time domain (SRS subframes), frequency domain(transmission combs “TC”) and code domain (cyclic shifts, CS). The terms“antenna” and “antenna port” may be used interchangeably with respect toSRS transmissions. Some of the methods or solutions described illustrate2 cell examples, Cell 1 and Cell 2. However, these solutions may beapplicable to any number of serving cells. Cell 1 may be any one of theserving cells and Cell 2 may be any other of the serving cells. Themethods or solutions may be used individually or in any combination. Theapplicable solutions, methods, and the like that may be used may dependon whether a scheduled SRS is a periodic SRS or an aperiodic SRS.

Described herein are methods for resource assignment of SRS subframes.In LTE R8/9, a R8/9 WTRU may transmit SRS in the last orthogonalfrequency division multiplexing (OFDM) symbol of the second time slot ofone SRS subframe per SRS periodicity T_(SRS) for FDD and for one or twoSRS subframes per SRS periodicity T_(SRS) for TDD. In an example methodfor LTE R10, a WTRU with multiple antennas may perform SRS transmissionin one or more subframes per SRS periodicity T_(SRS) including subframesthat are not WRTU-specific subframes. The WTRU may determine cellspecific subframes occurring within a given SRS periodicity, T_(SRS),and may use some of those subframes for transmission of SRS.

In LTE R8, the WTRU may be provided with a WTRU-specific configurationof subframes for SRS transmission to use once or until the configurationis disabled. In another example method for LTE R10, an additionalduration, D, may be provided such that given the duration D, the WTRUmay transmit SRS in each of the next D WTRU-specific SRS subframes. Thismay be referred to as multiple transmission SRS or multi-shot SRS andother details are described herein below. For example, multi-shot SRSmay be helpful for frequency hopping. For WTRUs with multiple antennas,the WTRU may transmit SRS for a different antenna (or multiple antennas)in each of the D subframes. The maximum number of antennas (or antennaports) for SRS transmission may be configured by higher layer signalingor may be signaled through Layer 1 (L1) signaling such as a downlinkcontrol information (DCI) format in a physical downlink control channel(PDCCH).

An activation time may be included with the configuration.Alternatively, an activation time and/or a trigger may be providedseparately such as by higher layers, (RRC signaling or medium accesscontrol (MAC) signaling), or by Layer 1 (L1) signaling such as through aDCI format in PDCCH. An activation time may indicate when to begintransmitting SRS. A trigger may indicate a request for SRS transmissionwhich, as a result of the trigger, may occur at a predefined orconfigured time relative to when the trigger was received. An activationtime may specify a specific subframe or system frame number, a subframewithin a system frame number, a subframe offset relative to the subframein which the activation time was received, or a subframe offset relativeto when a trigger is received.

As an alternative to modifying the existing WTRU-specific SRSconfiguration, a new SRS configuration may be defined which includes theduration and, optionally, an activation time.

In another example method for LTE R10, the WTRU may receive anindication from a base station, for example, N_(subframes) ^(SRS), whichdefines the number of subframes that the WTRU may use for SRStransmission for all its antennas. This indication, N_(subframes)^(SRS), may be configurable by higher layer signaling or may be signaledthrough a DCI format in the PDCCH. A different N_(subframes) ^(SRS)value may be provided for periodic SRS and aperiodic SRS. ForI<=N_(subframes) ^(SRS)<=the number of transmit antennas the WTRU has,multiple antenna ports may be mapped to an SRS subframe. For example,which antenna(s) to transmit in each subframe may be based on apre-defined rule (e.g., in order of antenna 1, 2, 3, 4). Alternatively,there may be no rule, since the base station may not know which antennais which. In this case, the WTRU may choose an order and may use thesame order all the time. An exception to this may be when an SRStransmission in a subframe is skipped due to a higher prioritytransmission. The SRS for the antenna planned for the next opportunitymay be transmitted in that opportunity (not the skipped antenna).

For illustrative purposes, if the indication N_(subframes) ^(SRS)=1,this may mean the WTRU may transmit SRS for all antennas in onesubframe. If the indication N_(subframes) ^(SRS)=2, this may mean thatthe WTRU may transmit SRS for its antennas over two subframes. For aWTRU with two antennas, this may mean to transmit SRS for each antennain a different subframe. For a WTRU with four antennas, this may meantransmit SRS for two antennas in one subframe and the other two antennasin a different subframe. If the indication N_(subframes) ^(SRS)=4, thismay mean the WTRU may transmit the SRS for its antennas over foursubframes. For a WTRU with four antennas, this may mean to transmit SRSfor the four antennas over four subframes, i.e., transmit SRS for eachantenna in a different subframe. In the case where the indicationN_(subframes) ^(SRS) is greater than the number of WTRU transmitantennas, multiple SRS subframes may be mapped to one antenna and theremay be a predefined rule as to on which antenna to transmit in eachsubframe. For example, if N_(subframes) ^(SRS) is twice the number ofantennas and the WTRU has two antennas, the rule may be to transmit onantenna 1, then antenna 2, then antenna 1, then antenna 2.

In another example method for LTE R10, given a trigger from the basestation to transmit SRS, the WTRU may transmit the SRS in either thenext cell-specific SRS subframe, the next WTRU-specific subframe, or thenext subframe of a set of subframes specifically assigned to the WTRUfor “on-demand” (also called aperiodic) type SRS transmission. Thetrigger may be via L1 signaling such as a DCI format or via higher layersignaling, (e.g., an RRC message). For higher layer signaling, anactivation time may need to be provided.

The WTRU may also receive an indication, together with the trigger, orseparately, indicating whether to transmit on all antennas, N,simultaneously, N/2 antennas in sequence, or N/4 antennas in sequence,(or N/X antennas where the value of X is known in some way).Alternatively, the number of antennas (or antenna ports) on which totransmit in sequence may be equal to the rank currently used for thephysical uplink shared channel (PUSCH). The rank, also known as thenumber of layers for MIMO transmission, may be derived from informationsignaled in an uplink (UL) grant DCI, for example an UL grant DCI thatis being used to trigger aperiodic SRS transmission.

FIG. 2 shows an example flowchart 200 for SRS transmission in responseto a trigger. A WTRU may receive a trigger from a base station (210).The WTRU may then transmit a SRS in a predetermined subframe inaccordance with the configuration (220). The trigger to transmit SRS maycome with an indication of how many subframes to use for thetransmission, (or the WTRU may receive this indication separately). AWTRU with N antennas may, if simultaneous transmission is indicated,send SRS on all N antennas at the next SRS transmission opportunity. Ifthe number of subframes to use is two, the WTRU may transmit on N/2antennas on the next SRS transmission opportunity, (e.g., antenna 1 and2 for N=4) and the other N/2 antennas on the second next SRStransmission opportunity, (e.g., antenna 3 and 4 for N=4). This may beapplicable for N even and >=2. If the number of subframes to use isfour, the WTRU may transmit on one antenna in each of the next four SRStransmission opportunities, cycling through each of the four transmitantennas in sequence. This may be applicable for N equal to a multipleof 4. The next SRS transmission opportunity may be the nextcell-specific SRS subframe, the next subframe in a new SRS configurationto be used for on-demand/aperiodic type SRS transmission, or the nextWTRU-specific SRS subframe. The method may be extended to more than fourantennas.

In another example method for LTE R10, if a WTRU skips a planned SRStransmission for a particular antenna, for example due to a conflictwith another transmission with a higher priority, the WTRU may in thenext SRS opportunity for this WTRU transmit the SRS for the antenna duefor that transmission (i.e., not transmit a SRS for the antennabelonging to the skipped opportunity).

In LTE R8, a WTRU may transmit SRS in the last OFDM symbol of the secondtimeslot, (i.e., the 14^(th) OFDM symbol in the normal CP mode), per SRSsubframe. In another example method for LTE R10, a R10 WTRU may use thelast OFDM symbol of both time slots, (i.e., the 7^(th) and 14^(th) OFDMsymbols in the normal CP mode), per SRS subframe.

For illustrative purposes only, an example of how the WTRU may use thecell-specific subframes between the WTRU-specific subframes with thenumber of subframes to use for multiple antenna SRS transmissionspecified is described. In a given WTRU-specific SRS period, the WTRUmay determine all of the cell-specific subframes in that period. Forexample, for srs-SubframeConfig=7, from Table 1, the cell-specificsubframes are specified by T_(SFC)=5 and Δ_(SFC)={0,1} which correspondsto subframes {0,1,5,6,10,11,15,16,20,21, . . . }. For I_(SRS)=7, fromTable 3, T_(SRS)=10 and T_(offset)=0 which corresponds to theWTRU-specific subframes {0,10, 20, 30, . . . }. The cell-specificsubframes in the first WTRU-specific period are {0,1,5,6}; and in thenext WTRU-specific period they are {10,11,15,16}. These will be referredto as the WTRU-permissable SRS subframes.

The WTRU may determine which of the WTRU-permissable SRS subframes touse for SRS transmission by a predetermined rule. For example, a rulemay select the first (or last) N_(subframes) ^(SRS) elements from theset. Another rule may select the first (or last) N_(subframes) ^(SRS)even (or odd) elements from the set. Another rule may select theN_(subframes) ^(SRS) elements evenly distributed within the set. Anotherrule may use some combination of the previous rules. Yet another rulemay select N_(subframes) ^(SRS) elements from the set according to apredetermined pattern. The predetermined pattern may be configurable byhigher layer signaling or signaled through L1 signaling, for example, aDCI format in PDCCH.

If srs-ConfigIndex I_(SRS), (which provides SRS periodicity T_(SRS) andSRS subframe offset T_(offset)) and/or N_(subframes) ^(SRS) is/areprovided separately for periodic and aperiodic SRS transmission, theWTRU may use the appropriate parameters according to the nature of theSRS transmission (periodic or aperiodic).

For the case of N_(subframes) ^(SRS)<=N_(Ant) ^(SRS), (i.e., where thenumber of SRS subframes is less than or equal to the number ofantennas), then in each of the selected N_(subframes) ^(SRS), the WTRUmay transmit SRS on the appropriate antenna(s). Let N_(Ant) ^(SRS) bedefined as the total number of antenna ports for a WTRU, then n_(Ant),the number of antenna ports from which SRSs are transmittedsimultaneously in one SRS subframe, may be determined asn_(Ant)=└N_(Ant) ^(SRS)/N_(subframes) ^(SRS)┘. If there are SRStransmissions in both time slots in one SRS subframe, n_(Ant)=└N_(Ant)^(SRS)/(2*N_(subframes) ^(SRS))┘.

If N_(subframes) ^(SRS)>N_(Ant) ^(SRS), then multiple SRS subframes maybe mapped to an antenna port depending on a predetermined rule. Forexample, one to one mapping sequentially, i.e., the first subframe tothe first antenna port and so on, and then cycling through, eventuallytransmitting SRS subsequent times for a given antenna port in one SRSperiodicity T_(SRS).

Described herein are example methods for resource assignment of cyclicshifts (CS) and transmission combs (TC). In an example method, a WTRUmay implicitly determine pairs of CSs and TCs for multiple antenna portsfrom a pair of CS and TC for a single antenna port. A WTRU with N_(Ant)^(SRS) antennas, N_(Ant) ^(SRS)>1, may derive the CS and/or TC forN_(Ant) ^(SRS)−1 of the antennas from the CS and/or TC the WTRU receivesfor one of the antennas. When a WTRU will transmit SRS simultaneously ona number of antennas, n_(Ant) which may be fewer than the number itphysically has, the WTRU may instead derive CS and/or TC for n_(Ant)−1of the antennas from the CS and/or TC the WTRU receives for one of theantennas. The number of antennas on which to transmit SRS simultaneouslymay be given or configured. It is noted that a cyclic shift may bedefined by two values, one being an integer which identifies a CS in aset of N_(CS) cyclic shifts and the actual CS which may be defined interms of the integer identifier. If the integer identifier is n_(SRS)and the actual cyclic shift is α_(SRS), the relationship between the twomay be defined as α_(SRS)=2π×n_(SRS)/N_(CS). The term cyclic shift or CSmay be used herein to represent the identifier or the actual cyclicshift. Based on the context, it will be clear to one skilled in the artwhich one is intended.

In another example method, a cyclic shift assigned to an antenna (orantenna port) may be based on a predefined rule. A predefined rule mayassign a cyclic shift to each antenna (or antenna port) to achieve thelargest distance between the cyclic shifts of the antennas (or antennaports). For example, for a set of cyclic shifts {0,1,2,3,4,5,6,7} andN_(Ant) ^(SRS)=2, if CS=2 for antenna port 1, then CS=6 for antenna port2. Maximal separation may be accomplished with the ruleCS_(m)=(CS_(ref)+m×γ)mod(N_(cs)), m=0, . . . , N_(Ant) ^(SRS)−1, whereCS_(ref) is the cyclic shift for a reference antenna (or antenna port)for which the WTRU receives the CS from the base station, N_(e), is thetotal number of cyclic shifts in a given CS set, CS_(m) is the cyclicshift for each antenna (antenna port) m, and γ may be defined asN_(cs)/N_(Ant) ^(SRS) in order to achieve the maximal separation. Whenthe WTRU will transmit SRS simultaneously on fewer antennas than itstotal number of antennas, maximal separation between the cyclic shiftsof those antennas may be achieved by replacing the total number ofantennas with the number of antennas used for transmission, i.e.,N_(Ant) ^(SRS) may be replaced by the number of antennas on which SRSwill be transmitted simultaneously, n_(Ant). Maximal distance betweencyclic shifts may maximize orthogonality and reduce interference. Theabove may be further illustrated with respect to flowchart 300 shown inFIG. 3. A WTRU may receive a CS for a given antenna/antenna port (310).The total number of cyclic shifts in a set may be signaled, given orconfigured (330). The total number of antennas or the number of antennason which to transmit SRS simultaneously, may be predetermined, given orconfigured (340). The WTRU may then determine the maximal separationbetween CSs in the cyclic shift set based on the received CS, the totalnumber of cyclic shifts and the number of antennas (350). The WTRU maythen assign a cyclic shift to an antenna based on the maximal or optimalcyclic shift separation (360).

Another predefined rule may assign the next to the current element in aset/group. For example, given a set of cyclic shifts {0,1,2,3,4,5,6,7}and N_(Ant) ^(SRS)=2, if CS=2 for antenna port 1, then CS=3 for antennaport 2. Another predefined rule may use a predetermined pattern, whichmay be configurable by higher layer signaling or signaled through L1signaling, for example, a DCI format in PDCCH.

In another example method, transmission combs may be assigned firstagainst a given cyclic shift and then the cyclic shifts next for alltransmit antenna ports, i.e., a new cyclic shift may be used after alltransmission combs are used for a given a given cyclic shift.Alternatively, the cyclic shifts may be assigned first for a giventransmission comb.

In another example method, the CSs and/or TCs for multiple antenna portsmay be cycled or hopped with a predetermined rule/pattern per subframeor per slot if two slots in one SRS subframe are used. Activation ofhopping and the predetermined rule/pattern may be configurable by higherlayer signaling or signaled through L1 signaling, for example, a DCIformat in PDCCH.

In another example method, one set of CSs may be assigned to periodicSRS and a second set may be assigned to aperiodic SRS. This may also beimplemented for TCs. The methods for assigning CS and TC may bepredetermined by a rule. For example, one rule may state that from allCS and/or TC, select the first n to be the set for periodic SRS and theremainder for aperiodic SRS. For illustrative purposes only, CS=0, 1, 2,3 and TC=0 for periodic SRS and CS=4, 5, 6, 7 and TC=1 for aperiodicSRS. Another rule may state that from all CS and/or TC, select the evennumbers for periodic SRS and the odd numbers for aperiodic SRS. Anotherrule may be a combination of the above. Another rule may select elementsfrom the set according to a predetermined pattern separately for bothperiodic and aperiodic SRS. The predetermined pattern may beconfigurable by higher layer signaling or signaled through L1 signaling,for example, a DCI format in PDCCH.

The following are illustrative examples for assigning subframes, cyclicshifts, and transmission combs in accordance with the example methodsdescribed herein above. In an aperiodic trigger example, a SRSindicator/request may be used for triggering aperiodic SRS transmissionand may, for example, be included with an UL grant. The parameterN_(subframes) ^(SRS) may be combined with the SRS indicator/request. Anexample is shown in Table 6 where two bits may be used to both triggerthe SRS transmission and to indicate how many subframes to use for SRStransmission.

TABLE 6 Value 00 01 10 11 Action No aperiodic SRS Trigger aperiodicTrigger aperiodic Trigger aperiodic (no aperiodic SRS transmission SRStransmission SRS transmission SRS/deactivate with N_(subframes) ^(SRS) =1 With N_(subframes) ^(SRS) = 2 with N_(subframes) ^(SRS) = 4 dynamicaperiodic SRS transmission)

The following are examples of resource assignment of SRS subframes. Inthese examples, SRS transmissions for multiple antenna ports are spreadover multiple subframes, (or one subframe), within WTRU-specific SRSperiodicity T_(SRS) and SRSs are transmitted in the last OFDM symbol(s),(14^(th) OFDM symbol or 7^(th) and 14^(th) in the normal CP mode), ofone SRS transmission subframe. To obtain SRS transmission instances, SRSsubframe offsets, T_(offset-R10), for multiple antenna ports aredetermined from the SRS subframe offset, T_(offset), configured byhigher layer signaling for a single antenna port, as follows.

First, compute cell-specific transmission offsets Δ_(SFC) ^(UE-specific)within a given WTRU-specific SRS periodicity T_(SRS) from the tablesabove (Table 1 and Table 3 for FDD), since WTRU-specific subframes mustbe within the cell-specific subframes allowed for SRS transmission. Thenumber of cell configuration periods within a SRS periodicity T_(SRS) iscomputed as n_(SFC) ^(SRS)=└T_(SRS)/T_(SFC)┘ where T_(SFC) is defined asa configuration period in Table 1 and T_(SFC)≤T_(SRS). Then the possibletransmission offsets for a WTRU-specific SRS periodicity T_(SRS) areΔ_(SFC) ^(UE-specific)∈{Δ_(SFC), T_(SFC)+Δ_(SFC),2*T_(SFC)+Δ_(SFC), . .. , (n_(SFC) ^(SRS)−1)*T_(SFC)+Δ_(SFC)} where i*T_(SFC)+Δ_(SFC)represents that all elements of a set Δ_(SFC) are added by i*T_(SFC). Inexample 1, srsSubframeConfiguration=0 (i.e. T_(SFC)=1, Δ_(SFC)={0} inTable 1) and I_(SRS)=7 (i.e. T_(SRS)=10 and T_(offset)=0 from Table 3),then Δ_(SFC) ^(UE-specific)∈{0,1,2,3,4,5,6,7,8,9} and in example 2,srsSubframeConfiguration=7 (i.e. T_(SFC)=5, Δ_(SFC)={0,1} in Table 1)and I_(SRS)=7 (i.e. T_(SRS)=10 and T_(offset)=0 from Table 3), thenΔ_(SFC) ^(UE-specific)∈{0,1,5,6} for n_(SFC) ^(SRS)=└T_(SRS)/T_(SFC)┘=2.

Then, select d_(subframe-offset)(i) for i=0, 1, . . . , N_(subframes)^(SRS)−1 out of Δ_(SFC) ^(UE-specific) based on predetermined rules.Examples of predetermined rules are described herein. One rule mayselect first N_(subframes) ^(SRS) elements from the set of Δ_(SFC)^(UE-specific), for example d_(subframe-offset) (0)=0,d_(subframe-offset) (1)=1 for N_(subframe) ^(SRS)=2 and Δ_(SFC)^(UE-specific)∈{0,1,5,6} Another rule may select N_(subframes) ^(SRS)even elements from Δ_(SFC) ^(UE-specific), for exampled_(subframe-offset) (0)=0, d_(subframe-offset) (1)=5 for N_(subframes)^(SRS)=2 and Δ_(SFC) ^(UE-specific)∈{0,1,5,6} Another rule may selectN_(subframes) ^(SRS) odd elements from Δ_(SFC) ^(UE-specific), forexample d_(subframe-offset)(0)=1, d_(subframe-offset)(1)=6 forN_(subframes) ^(SRS)=2 and Δ_(SFC) ^(UE-specific)∈{0,1,5,6} Another rulemay select N_(subframes) ^(SRS) elements evenly distributed withinΔ_(SFC) ^(UE-specific), for example d_(subframe-offset)(0)=0,d_(subframe-offset) (1)=5 for N_(subframes) ^(SRS)=2 and Δ_(SFC)^(UE-specific)∈{0,1,2,3,4,5,6,7,8,9}.

Then, compute SRS transmission subframes within UE-specific SRSperiodicity T_(SRS), T_(offset-R10):T_(offset-R10)(i)=(T_(offset)+d_(subframe-offset)(i))modT_(SRS), wherei=0, 1, . . . , N_(subframes) ^(SRS)−1.

Described herein are examples of CS and TC assignments. A firstillustrative example assigns CS first and then TC. In this method, thetransmission combs for simultaneous SRS transmission from n_(Ant) may bekept the same as k_(TC) configured semi-statically by higher layersignaling for a single antenna port until all cyclic shifts areexhausted. The actual cyclic shifts α_(SRS-R10) for simultaneous SRStransmission from n_(Ant) are implicitly determined from n_(SRS) ^(cs),a reference cyclic shift identifier, which may be configuredsemi-statically by higher layer signaling for a single antenna port.

An example for assigning CS in a manner which achieves an evendistribution of cyclic shifts is as follows. A delta between CS offsets,d_(offset) ^(CS)=N_(CS)/n_(Ant), may be computed, where N_(CS) is thetotal number of cyclic shifts, for example N_(CS)=8, {0,1, . . . , 7} or12 for the extended CS. Then the actual cyclic shifts α_(SRS-R10) forn_(Ant) are computed as follows:

$\begin{matrix}{{n_{{SRS}\text{-}R\; 10}^{cs}(i)} = {\left\lbrack {n_{SRS}^{cs} + \left( {i*d_{offset}^{CS}} \right)} \right\rbrack {mod}\; N_{CS}}} & {{Equation}\mspace{14mu} 1} \\{{\alpha_{{SRS}\text{-}R\; 10}(i)} = {2\pi \frac{n_{{SRS}\; \text{-}R\; 10}^{cs}(i)}{N_{cs}}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

where i=0, 1,2, . . . , (n_(Ant)−1). This determination results inmaximally spacing cyclic shifts as shown herein above in FIG. 3.

Another example is to select CS offsets based on a predeterminedrule/pattern from a predetermined set, for example, assign even cyclicshifts (e.g., 0,2,4,6) for periodic SRS and odd cyclic shifts (e.g.,1,3,5,7) for aperiodic SRS.

The following are examples illustrating the combination of CS assignmentwith using subframes between WTRU-specific subframes for SRStransmission on multiple antennas. For illustrative purposes, thefollowing WTRU-specific parameters and example values are used: N_(TC)^(UE) is the total number of transmission combs, k_(TC-R10) identifieswhich transmission comb in a set of transmission combs to use, n_(SRS)^(cs) is a reference cyclic shift to use for SRS transmission. ForN_(TC) ^(UE)=2, k_(TC-R10)∈{0, 1}, (or for extended TCs, N_(TC) ^(UE)=4,and k_(TC-R10)∈{0,1, 2, 3}); for N_(CS)=8, b_(SRS) ^(cs)∈{0,1, . . . ,7}; in the examples, we will use I_(SRS)=7 which corresponds toT_(SRS)=10 and T_(offset)=0 from Table 3, srs-SubframeConfig=0 whichcorresponds to Δ_(SFC)=0 from Table 1, k_(TC-R10)=0 unless another TC isneeded, and n_(SRS) ^(cs)=2.

Throughout the following examples, assignment of cyclic shifts tomultiple antenna ports may use the even distribution method noted above.Selection of the subframes to use between the WTRU-specific subframesmay be based on a predetermined rule such as one described herein oranother rule. Note that all figures represent two or three SRSperiodicities. Only one SRS periodicity T_(SRS) is needed for “one shot”dynamic aperiodic SRS.

In one example, SRS multiplexing by cyclic shifts using the samesubframes and same TC used for all antenna ports is described for thecase of 2 antennas. In this case, transmission is only in theWTRU-specific subframes. For N_(Ant) ^(SRS)=2 and N_(subframes)^(SRS)=1, n_(Ant)=2. Using the even distribution rule noted above, the(CS, TC) pair is (2, 0) for antenna port 0 (A0), and (6, 0) for antennaport 1 (A1) as illustrated in FIG. 4.

For the example of 2 antennas, SRS multiplexing and capacity increasemay be accomplished by using time division multiplexing (TDM), whereindifferent subframes are used for SRS transmission while using the, sameTC and CS. For N_(Ant) ^(SRS)=2 and N_(subframes) ^(SRS)=2, n_(Ant)=1.Based on a predefined rule such as even separation in time,T_(offset-R-10) (0)=0 and T_(offset-R10) (1)=5 Using the evendistribution rule noted above, the (CS, TC) pair for each antenna portis (2, 0) as shown in FIG. 5.

In another example, SRS multiplexing by CS using the same subframe andthe same TC for all antennas is described for the case of 4 antennas.For N_(Ant) ^(SRS)=4 and N_(subframe) ^(SRS)=1, n_(Ant)=4. Using theeven distribution rule above, the (CS, TC) pairs for the antenna portsare (2, 0) for antenna port 0 (A0), (4, 0) for antenna port 1 (A1), (6,0) for antenna port 2 (A2), and (0, 0) for antenna port 3 (A3) asillustrated in FIG. 6.

In another example, SRS multiplexing by TDM and CS while using the sameTC for the case of 4 antennas is described. For N_(Ant) ^(SRS)=4 andN_(subframes) ^(SRS)=2, n_(Ant)=2. Based on a predefined rule such aseven separation in time, T_(offset-R10) (0)=0 and T_(offset-R10) (1)=5Using the even distribution rule noted above and n_(Ant)=2, the (CS, TC)pairs for the antenna ports are (2, 0) for antenna ports 0 and 2 (A0 andA2) and (6, 0) for antenna ports 1 and 3 (A1 and A3) as shown in FIG. 7.

In another example, SRS multiplexing by TDM using the same CS and thesame TC for all antennas is described for the case of 4 antennas. ForN_(Ant) ^(SRS)=4 and N_(subframes) ^(SRS)=4, n_(Ant)=1. This correspondsto transmitting SRS on one antenna in a subframe. Using a predefinedrule may result in T_(offset-R10)(0)=0, T_(offset-R10)(1)=2,T_(offset-R10) (2)=4, and T_(offset-R10) (3)=6 Using the evendistribution rule noted above, and n_(Ant)=1, the (CS, TC) pairs for theantenna ports are all (2, 0) as shown in FIG. 8.

Described herein are illustrative examples for assigning TC first andthen CS. In this method, the transmission combs for all transmit antennaports are implicitly determined from the transmission comb k_(TC)configured by higher layer signaling for a single antenna port orpredetermined by a rule. For example, if the total number oftransmission combs defined as N_(TC) ^(UE) is 2, k_(TC-R10) ∈{0, 1},then the rule may be k_(TC-R10)(0)=k_(TC) andk_(TC-R10)(1)=(k_(TC)+1)mod 2.

SRS subframe offsets T_(offset-R10) for multiple antenna ports may bedetermined from T_(offset) configured by higher layer signaling for asingle antenna port in the same way as described above.

To assign a pair of orthogonal resources of CS and TC to each antennaport, TCs are assigned for a given CS until all TCs are exhausted. Forthe examples associated with FIGS. 4 and 7, the (CS, TC) pairs wouldbecome (2, 0) for antenna 0 and (2, 1) for antenna 1. For the exampleassociated with FIG. 6, the (CS, TC) pairs would become (2, 0) forantenna 0 (A0), (2, 1) for antenna 1 (A1), (6, 0) for antenna 2 (A2),and (6, 1) for antenna 3 (A3).

Described herein are methods for using different types of UL grants astriggers for aperiodic SRS transmissions. In a solution for anon-semi-persistent scheduling case, a WTRU may receive both explicitand implicit UL grants. The WTRU may interpret one or more of thesegrants as an aperiodic SRS trigger without the need for additionalsignaling, (e.g., added trigger bit(s)), being provided with the grant.

The WTRU may determine which UL grant type(s) to interpret as theaperiodic SRS trigger based on the configuration provided by the basestation, for example, via RRC signaling. Alternatively, it may bepredefined as to which UL grant types(s) are to be interpreted asaperiodic SRS triggers. For example, the network may transmit a new RRCmessage or add a field in an existing RRC message to define aninstruction that indicates whether an UL grant with new transmissionand/or an UL grant with only retransmission, and/or an implicit UL grantvia physical hybrid automatic repeat request (ARQ) indicator channel(PHICH) negative acknowledgement (NACK) is to be interpreted as theaperiodic SRS trigger. The WTRU then acts accordingly when receiving anUL grant.

A new field, for example UL-Grant-Type, may be added as a LTE R10extension to the SoundingRS-UL-ConfigDedicated information element (IE)to indicate for aperiodic SRS which type(s) of UL grant triggeraperiodic SRS. For example, the new field may indicate which of UL grantwith new transmission, UL grant with only retransmission, and UL grantvia PHICH NACK will trigger aperiodic SRS. Alternatively, if a new IE isdefined for aperiodic SRS, then the new field may be added to that IE.

In an example of the first solution, a new data grant may triggeraperiodic SRS. The WTRU may interpret a PDCCH with UL grant as anaperiodic SRS trigger if there is new data to be transmitted for atleast one of the codewords, for example, when at least one of the newdata indicator (NDI) bits indicates new data. When the PDCCH UL grantindicates retransmission for all the codewords, the WTRU does notinterpret the PDCCH with UL grant to be an aperiodic SRS trigger. TheWTRU does not interpret the implicit resource assignment by way of PHICHNACK as a trigger for aperiodic SRS.

In another example of the first solution, an explicit retransmissionrequest may trigger aperiodic SRS. The WTRU may interpret PDCCH with ULgrant as an aperiodic SRS trigger if the UL grant indicatesretransmission only, (for all of the codewords). In this case all NDIbits may indicate retransmission, (no new data). The base station maychoose to set the NDI bits in this manner to “force” an aperiodic SRSwith a small penalty of an unnecessary retransmission. In this example,the UL grant indicating retransmission for all may be the only UL grantthat triggers aperiodic SRS. Alternatively, the WTRU may also interpretPDCCH UL grant with new data, (for one or more code words) as anaperiodic SRS trigger. In another alternative, the WTRU may alsointerpret an implicit UL grant via PHICH NACK as an aperiodic SRStrigger.

In another example of the first solution, a PHICH NACK may triggeraperiodic SRS. The WTRU may only interpret an implicit PHICH NACK grantas an aperiodic SRS trigger. Alternatively, the WTRU may also interpreta PDCCH UL grant with new data, (for one or more code words), as anaperiodic SRS trigger. In another alternative, the WTRU may alsointerpret a PDCCH UL grant indicating retransmission for all code wordsas an aperiodic SRS trigger.

In another example of the first solution, any UL grant may triggeraperiodic SRS. The WTRU may interpret a PDCCH UL grant with new data,(for one or more code words), as an aperiodic SRS trigger. The WTRU mayalso interpret a PDCCH UL grant indicating retransmission for all codewords as an aperiodic SRS trigger. The WTRU may also interpret animplicit PHICH NACK grant as an aperiodic SRS trigger.

In a second solution, for the case of semi-persistent scheduling (SPS),the network may send the WTRU a first transmission grant and a periodicallocation. After that point, the WTRU may not receive any more explicitUL grants. Grants may be implicit by the SPS allocation and by PHICHNACK. Interpretation of these UL grants may be as follows. For the caseof SPS, the WTRU may interpret some combination of the firsttransmission grant, the subsequent implicit UL grants based on the SPSschedule, and each PHICH NACK as an aperiodic SRS trigger. In anotherexample for the case of SPS, the WTRU may interpret only the firsttransmission grant as an aperiodic SRS trigger. In another example forthe case of SPS, the WTRU may interpret the first transmission grant andeach subsequent implicit UL grant based on the SPS schedule as anaperiodic SRS trigger. In another example for the case of SPS, the WTRUmay interpret the first transmission grant and each PHICH NACK as anaperiodic SRS trigger. In another example for the case of SPS, the WTRUmay interpret the first transmission grant, each subsequent implicit ULgrant based on the SPS schedule and each PHICH NACK as an aperiodic SRStrigger.

In a third solution, for the case where an explicit trigger is includedwith the initial UL grant and that explicit trigger requested SRS, thenthe WTRU may interpret subsequent UL grants, (via PDCCH and/or PHICHNACK) to be aperiodic SRS trigger.

Described herein are methods for scheduling SRS in the absence of data,(a dummy grant). It may be necessary to schedule aperiodic SRS in theabsence of physical uplink shared channel (PUSCH) data to transmit inthe UL. This may be useful, for example, if it has been a long timesince the last SRS transmission and the base station may want soundingmeasurements to effectively allocate resources. Having measurements fromSRS may help the base station make a better decision.

In a first solution, the base station may send a downlink controlinformation (DCI) format, for example, an UL PUSCH grant message, withcodepoints indicating SRS only. For example, the modulation and codingset (MCS) index for each codeword (CW) may be set to a reserved value,(e.g., 29 to 31), while the NDI for each CW is toggled, indicating a newtransmission. In LTE R8/9, this is an invalid combination since the MCSneeds to be signaled for a new transmission. This combination may bespecified in LTE R10 to indicate that a CW is disabled. If the WTRUreceives an UL grant with field(s) set to indicate that both codewordsare disabled, the WTRU may interpret that as an SRS trigger.

The WTRU may use the existing content of the UL grant to obtain otherconfiguration information. For example, the WTRU may determine thecomponent carrier (CC) on which to transmit the SRS from the UL grant inthe same manner that the WTRU determines what CC the UL grant is for.Alternatively, the CC on which to transmit may be fixed as all UL CCs,all active UL CCs, or the UL CCs may be designated in some other mannersuch as by higher layer signaling. The WTRU may obtain additionalconfiguration data from bits in the DCI format whose purpose may havebeen modified from their original purpose in the UL grant.

In another solution, the UL grant DCI format for LTE R10 may need to bea modified version of the LTE R8/9 UL grant format, (DCI format 0), inorder to at least accommodate multiple antennas. There may be two NDIbits to indicate whether the grant is for new or retransmitted data foreach of the two codewords. For the case of using the UL grant as an SRStrigger in the absence of data, the WTRU may interpret the 2 NDI bits toindicate on which antenna to transmit the SRS.

Described herein are methods for handling multiple antennas. In LTE R10,a WTRU may support up to 4 antennas. The first set of solutions may useantenna-specific configurations and SRS triggers. In the first solution,a WTRU may receive antenna-specific subframe and transmission parameterconfigurations from the base station, for example, by RRC signaling.These antenna-specific configuration(s) may be similar in definition andcontent to the WTRU-specific SRS configuration currently defined for LTER8 periodic SRS.

A LTE R8/9 WTRU-specific subframe configuration consists of a tablewhich maps an SRS configuration index to a period in subframes and asubframe offset. In one example of the first solution, the same, or asimilar, table may be used or LTE R10. The WTRU may then receive anindex into the table for each antenna instead of a single WTRU-specificvalue. Using this index the WTRU knows the SRS subframe allocation foreach antenna.

LTE R8/9 WTRU-specific parameters are provided to the WTRU using the IEshown in Table 7, received via dedicated RRC signaling.

TABLE 7 SoundingRS-UL-ConfigDedicated ::= CHOICE{  release NULL,  setupSEQUENCE {   srs-Bandwidth  ENUMERATED {bw0, bw1, bw2, bw3},  srs-HoppingBandwidth  ENUMERATED {hbw0, hbw1, hbw2, hbw3},  fregDomainPosition   INTEGER (0..23),   duration  BOOLEAN,  srs-ConfigIndex   INTEGER (0..1023),   transmissionComb  INTEGER(0..1),   cyclicShift   ENUMERATED {cs0, cs1, cs2, cs3, cs4, cs5, cs6,cs7}  }

In another example of the first solution, in order for antenna-specificconfigurations in LTE R10 to provide the most flexibility, the WTRU mayreceive a separate value of each of the applicable parameters in this IEfor each of its antennas. The values may be the same or different foreach of the antennas. The parameter srs-ConfigIndex may be set to thesame value for one or more antennas to configure SRS transmission forthose antennas in the same subframe, (assuming simultaneous transmissionis allowed and if necessary, configured).

The duration parameter in this IE is intended for periodic SRS, notaperiodic SRS and, therefore has a BOOLEAN value of single orindefinite. For aperiodic SRS, this value may be eliminated if onlyone-shot aperiodic transmissions are allowed. If multi-shot aperiodictransmissions are allowed, the duration may be used to indicate thenumber of transmissions, for example, one for one-shot, two for twotransmissions, Ns for Ns transmissions or a value to represent each ofthe allowed number of transmissions. It may also include a value toindicate continuous until deactivation.

An example of the IE for antenna-specific aperiodic SRS configuration,called here SoundingRS-UL-ConfigDedicated-r10, is shown in Table 8. Itmay consist of a separate set of parameters for each of the WTRU'santennas. The definitions of the parameters, as modified from LTE R8,are provided below after the examples.

TABLE 8 SoundingRS-UL-ConfigDedicated-r10 ::= CHOICE{   release  NULL,  Setup  SEQUENCE {    Num-WTRU-Ant-v10-x0  ENUMERATED { ant-2, ant-4},OPTTIONAL -— Cond multiAnt    Setup-r10-multi-Ant-List := SEQUENCE (SIZE(1..maxWTRUAnt)) OF Setup-r10-multi-Ant-r10  } } Setup-r10-multi-Ant-r10      SEQUENCE {    srs-Bandwidth ENUMERATED {bw0, bw1, bw2, bw3},OPTIONAL -- Cond MultiAnt    srs-HoppingBandwidth ENUMERATED {hbw0,hbw1, hbw2, hbw3}, OPTIONAL -- Cond MultiAnt    freqDomainPositionINTEGER (0..23), OPTIONAL -- Cond MultiAnt    srs-ConfigIndex INTEGER(0..1023), OPTIONAL -- Cond MultiAnt    transmissionComb INTEGER (0..1),OPTIONAL -- Cond MultiAnt    cyclicShift ENUMERATED {cs0, cs1, cs2, cs3,cs4, cs5, cs6, cs7} OPTIONAL -- Cond MultiAnt   duration-Aperiodic-v10-x0 ENUMERATED (Ap-1, Ap-2, Ap-3, Ap-4,Ap-5,...,Ap-Ns), OPTIONAL -- Cond MultiAnt }

Another example of the IE for antenna-specific aperiodic SRSconfiguration, called here SoundingRS-UL-ConfigDedicated-r10, is shownin Table 9. It may consist of a set of common parameters that are thesame for all the antennas. For the parameters which may be different foreach antenna, the IE may include separate parameters for each of theWTRU's antennas. In this example, only the subframe configuration index,the cyclic shift, and the transmission comb may be different for each ofthe antennas. The definitions of the parameters, as modified from LTER8, are given after the examples.

TABLE 9 SoundingRS-UL-ConfigDedicated-r10 ::=   CHOICE{  release NULL, Setup SEQUENCE {   srs-Bandwidth  ENUMERATED {bw0, bw1, bw2, bw3},  srs-HoppingBandwidth  ENUMERATED {hbw0, hbw1, hbw2, hbw3},  fregDomainPosition  INTEGER (0..23),   duration-Aperiodic-v10-x0 ENUMERATED (Ap-1, Ap-2, Ap-3, Ap-4, Ap-5,...,Ap-Ns),  Num-WTRU-Ant-v10-x0  ENUMERATED { ant-2, ant-4}, OPTIONAL -- CondmultiAnt   WTRU-Ant-Specific-List :=  SEQUENCE (SIZE (1..maxWTRUAnt)) OFWTRU-Ant-Specific-r10, } WTRU-Ant-Specific-r10   SEQUENCE {  srs-ConfigIndex    INTEGER (0..1023), OPTIONAL -- Cond MultiAnt  transmissionComb    INTEGER (0..1), OPTIONAL -- Cond MultiAnt  cyclicShift    ENUMERATED {cs0, cs1, cs2, cs3, cs4, cs5, cs6, cs7}OPTIONAL -- Cond MultiAnt

Another example of the IE for antenna-specific aperiodic SRSconfiguration, called here SoundingRS-UL-ConfigDedicated-r10, is shownin Table 10. It may consist of a set of common parameters that are thesame for all the antennas. For the parameters which may be different foreach antenna, the IE may include separate parameters for each of theWTRU's antennas. In this example, only the cyclic shift, and thetransmission comb may be different for each of the antennas. Thedefinitions of the parameters, as modified from LTE R8, are given afterthe examples.

TABLE 10 SoundingRS-UL-ConfigDedicated-r10 ::=   CHOICE{  release NULL, Setup SEQUENCE {   srs-Bandwidth  ENUMERATED {bw0, bw1, bw2, bw3},  srs-HoppingBandwidth  ENUMERATED {hbw0, hbw1, hbw2, hbw3},  fregDomainPosition  INTEGER (0..23),   srs-ConfigIndex  INTEGER(0..1023),   duration-Aperiodic-v10-x0  ENUMERATED (Ap-1, Ap-2, Ap-3,Ap-4, Ap-5,...,Ap-Ns),   Num-WRU-Ant-v10-x0  ENUMERATED { ant-2, ant-4},OPTIONAL -- Cond multiAnt   WTRU-Ant-Specific-List :=  SEQUENCE (SIZE(1..maxWTRUAnt)) OF WTRU-Ant-Specific-r10, } WTRU-Ant-Specific-r10  SEQUENCE {   transmissionComb    INTEGER (0..1), OPTIONAL -- CondMultiAnt   cyclicShift    ENUMERATED {cs0, cs1, cs2, cs3, cs4, cs5, cs6,cs7} OPTIONAL -- Cond MultiAnt

The parameter field descriptions shown in Table 11 may apply to theabove examples.

TABLE 11 SoundingRS-UL-ConfigDedicated-R10 field descriptionsNum-WTRU-Ants-v10-x0 The number of WTRU antennas to be activated, 2 or4. Default is 1 and the parameter will not be transmitted. srs-BandwidthParameter: B_(SRS), see TS 36.211 [21, tables 5.5.3.2-1, 5.5.3 2-2,5.5.3 2-3 and 5.5.3.2-4]. In case of multiple WTRU antenna case, seeConditional Presence explanation below. freqDomainPosition Parameter:n_(RRC,) see TS 36.211 [21, 5.5.3.2]. In case of multiple WTRU antennacase, see Conditional Presence explanation below. srs-HoppingBandwidthParameter: SRS hopping bandwidth b_(hop) ∈ {0, 1, 2, 3}, see TS 36.211[21, 5.5.3.2] where hbw0 corresponds to value 0, hbw1 to value 1 and soon. In case of multiple WTRU antenna case, see Conditional Presenceexplanation below. DurationAperiodic-v10x0 Parameter: Duration. See TS36.213 [21, 8.2], for periodic SRS, oneP, corresponds to “single” andvalue InfiP to “indefinite”. For aperiodic SRS, Ap-1 indicatesone-trans- mission, Ap-2 means 2 and so on. In case of multiple WTRUantenna case, see Conditional Presence explanation below.srs-ConfigIndex Parameter: I_(SRS). See TS 36.213 [23, table8.2-1]. Incase of multiple WTRU antenna case, see Conditional Presence explanationbelow. transmission Comb Parameter: k_(TC) ∈ {0,1} , see TS 36.211 [21,5.5.3.2]. In case of multiple WTRU antenna case, see ConditionalPresence explanation below. cyclicShift Parameter: n_SRS. See TS 36.211[21, 5.5.3.1], where cs0 corresponds to 0 etc. In case of multiple WTRUantenna case, see Conditional Presence explanation below. Conditionalpresence Explanation multiAnt For multiple WTRU antenna list Setup-r10-multi-Ant-List or WTRU-Ant-Specific-List case, the value of thisparameter for the first list entry must be present for antenna-1; itwill be present for subsequent activating antenna(s) only if theparameter value is different than that in the previous entry. In absenceof the parameter value, the value of it in a previous list entry isapplied.

In LTE R8, the IE SoundingRS-UL-ConfigDedicated may be included in theIE PhysicalConfigDedicated of the RadioResourceConfigDedicatedstructure. The RadioResourceConfigDedicated is called on by theRRCConnectionSetup message, the RRCConnectionReconfiguration message andthe RRCReestablishmentRequest message.

The LTE R10 WTRU antenna-specific configurations may be included in theRRC configuration messages by including the new structure, calledSoundingRS-UL-ConfigDedicated-r10 herein, into the IEPhysicalConfigDedicated, which may then be included in the RRC downlinkconfiguration messages as in the above LTE R8 case. The changes to theIE PhysicalConfigDedicated may be as shown in Table 12.

TABLE 12 PhysicalConfigDedicated information element -- ASN1STARTPhysicalConfigDedicated ::= SEQUENCE {  pdsch-ConfigDedicatedPDSCH-ConfigDedicated  OPTIONAL, -- Need ON  pucch-ConfigDedicatedPUCCH-ConfigDedicated  OPTIONAL, -- Need ON  pusch-ConfigDedicatedPUSCH-ConfigDedicated  OPTIONAL, -- Need ON  uplinkPowerControlDedicatedUplinkPowerControlDedicated  OPTIONAL, -- Need ON  tpc-PDCCH-ConfigPUCCHTPC-PDCCH-Config  OPTIONAL, -- Need ON  tpc-PDCCH-ConfigPUSCHTPC-PDCCH-Config  OPTIONAL, -- Need ON  cqi-ReportConfigCQI-ReportConfig  OPTIONAL, -- Need ON  soundingRS-UL-ConfigDedicatedSoundingRS-UL-ConfigDedicated  OPTIONAL, -- Need ON  antennaInfo CHOICE{   explicitValue  AntennaInfoDedicated,   defaultValue  NULL  }  OPTIONAL, -- Need ON  schedulingRequestConfig SchedulingRequestConfigOPTIONAL, -- Need ON  . . . ,  physicalConfigDedicated-v9x0PhysicalConfigDedicated-v9x0-IEs   OPTIONAL -- Need ON physicalConfigDedicated-v10x0 PhysicalConfigDedicated-v10x0-IEs  OPTIONAL -- Need ON } PhysicalConfigDedicated-v10x0-IEs ::=   SEQUENCE {  SoundingRS-UL-ConfigDedicated-v10x0SoundingRS-UL-ConfigDedicated-r10    OPTIONAL,-- Need ON }

In another example, the antenna-specific configuration may include theparameters for one antenna and then parameters for any or all of theother antennas only if they were different from the parameters for oneantenna.

If frequency hopping is not used for aperiodic SRS, the relatedparameters may be excluded from the IE.

In a second solution, a WTRU may receive antenna-specific subframe andtransmission parameter configurations from the base station. Given atrigger, the WTRU may transmit SRS in the next antenna-specific subframefor each of the antennas for which SRS transmission is configured. Theantenna-specific subframes may be the same or different for thedifferent antennas. When certain parameters are the same for differentantennas, those parameters may need to be signaled once, (i.e., ascommon for all antennas), and then be used for all the antennas.

In an example of the second solution, a WTRU may be configured fortransmission of SRS on Na antennas. Let the subframe configuration foreach antenna be defined for LTE R10 SRS in a manner similar to LTE R8SRS in that subframe periodicity T_(SRS)(i) and subframe offsetT_(offset)(i) are provided for each antenna i=0, 1, . . . Na−1. Then forthe frequency division duplex (FDD) case, given an SRS trigger insubframe ‘n’ the WTRU may transmit SRS for each antenna i, where i=0, 1,. . . Na−1, in subframe ‘k_(SRS) (i)’ such that k_(SRS) (i)>=n+1 andalso satisfies the antenna-specific SRS subframe offset and SRSperiodicity configuration parameters (10·n_(f)+k_(SRS) (i)−T_(offset)(i)) mod T_(SRS) (i)=0.

If T_(SRS)(i) and T_(offset)(i) are the same for all antennas, their SRStransmissions may all occur in the same subframe. If there are Naantennas and their offsets are all different, the trigger may result inSRS transmissions in Na separate subframes.

In a third solution, a WTRU may receive antenna-specific subframe andtransmission parameter configurations from the base station. Given atrigger, the WTRU may transmit SRS in the next antenna-specific subframethat is at least four subframes from the triggering subframe for each ofthe antennas for which SRS transmission is configured. Theantenna-specific subframes may be the same or different for thedifferent antennas. When certain parameters are the same for differentantennas, those parameters may be signaled once, (i.e., as common forall antennas), and then be used for all the antennas.

In an example of the third solution, a WTRU may be configured fortransmission of SRS on Na antennas. Let the subframe configuration foreach antenna be defined for LTE R10 SRS in a manner similar to LTE R8SRS in that a subframe periodicity T_(SRS)(i) and subframe offsetT_(offset)(i) are provided for each antenna i=0, 1, . . . Na−1. Then forthe FDD case, given an SRS trigger in subframe ‘n’, the WTRU maytransmit SRS for each antenna i, where i=0, 1, . . . Na−1, in subframe‘k_(SRS) (i)’ such that k_(SRS)(i)>=n+4 and also satisfies theantenna-specific SRS subframe offset and SRS periodicity configurationparameters (10·n_(f)+k_(SRS)(i)−T_(offset) (i)) mod T_(SRS)(i)=0.

If T_(SRS)(i) and T_(offset)(i) are the same for all antennas, their SRStransmissions will all occur in the same subframe. If there are Naantennas and their offsets are all different, the trigger will result inSRS transmissions in Na separate subframes.

In a fourth solution, a WTRU may receive WTRU-specific subframes fromthe base station to use for all antennas for aperiodic SRS. Thesesubframes may be the same or different from the subframes to use forperiodic SRS. The transmission parameters such as cyclic shift andtransmission comb may be the same or different for the differentantennas. In case of simultaneous transmission from multiple antennas ina subframe, orthogonality may be achieved by cyclic shift multiplexingand/or different transmission comb assignments. Given a trigger, theWTRU may determine on which antenna(s) to transmit SRS and in whichsubframes based on the defined antenna designation method and thedefined trigger to transmission subframe relationship.

In an example of the fourth solution, a trigger, such as an UL grant orother DCI format, may explicitly specify on which antenna(s) to transmitSRS. In this case the WTRU may transmit SRS for the designatedantenna(s) in the next subframe that satisfies the defined trigger totransmission subframe relationship. Alternatively, higher layerconfiguration, such as via RRC signaling, may define on what antenna(s)to transmit SRS for each trigger.

For instance, given a trigger in subframe n, the WTRU may transmit SRSfor the designated antenna(s) in one of: 1) the next subframe (n+1); 2)the next cell-specific subframe, (for example subframe ‘k_(SRS)’ suchthat k_(SRS)>=n+1 and also satisfies the cell-specific SRS subframeoffset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC)); 3) the next WTRU-specific subframe, (forexample for FDD, subframe ‘k_(SRS)’ such that k_(SRS)>=n+1 and alsosatisfies the WTRU-specific SRS subframe offset and SRS periodicityconfiguration parameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0); 4)the next cell-specific subframe at least four subframes after thetriggering subframe, (for example subframe ‘k_(SRS)’ such thatk_(SRS)>=n+4 and also satisfies the cell-specific SRS subframe offsetand SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC)); or 5) the next WTRU-specific subframe atleast four subframes after the triggering subframe, (for example forFDD, subframe ‘k_(SRS)’ such that k_(SRS)>=n+4 and also satisfies theWTRU-specific SRS subframe offset and SRS periodicity configurationparameters (10 n_(f)+k_(SRS)−T_(offset)) modT_(SRS)=0).

In another example of the fourth solution, a trigger, such as an ULgrant or other DCI format, or higher layer signaling may designate thattransmission of SRS may be cycled through the antennas configured forSRS transmission. In this case, the WTRU may transmit SRS for theconfigured antennas, cycling through the antennas, in the next subframesthat satisfy the defined trigger to transmission subframe relationship.

Given a trigger in subframe n, the WTRU may transmit SRS for each of theNa configured antenna(s) in sequence according to one of the methodsdescribed below. In an example method, the WTRU may transmit SRS for thefirst configured antenna in the next cell-specific subframe, (forexample subframe ‘k_(SRS)’ such that k_(SRS)>=n+1 and also satisfies thecell-specific SRS subframe offset and SRS periodicity configurationparameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC)). The WTRU may transmit SRS foreach additional configured antenna, in each of the next cell specificsubframes.

In another example method, the WTRU may transmit SRS for the firstconfigured antenna in the next WTRU-specific subframe, (for example forFDD, subframe ‘k_(SRS)’ such that k_(SRS)>=n+1 and also satisfies theWTRU-specific SRS subframe offset and SRS periodicity configurationparameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0). The WTRU maytransmit SRS for each additional configured antenna, in each of the nextWTRU-specific subframes.

In another example method, the WTRU may transmit SRS for the firstconfigured antenna in the next cell-specific subframe, (for example,subframe ‘k_(SRS)’ such that k_(SRS)>=n+4 and also satisfies thecell-specific SRS subframe offset and SRS periodicity configurationparameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC)). The WTRU may transmit SRS foreach additional configured antenna, in each of the next cell specificsubframes.

In another example method, the WTRU may transmit SRS for the firstconfigured antenna in the next WTRU-specific subframe, (for example forFDD, subframe ‘k_(SRS)’ such that k_(SRS)>=n+4 and also satisfy theWTRU-specific SRS subframe offset and SRS periodicity configurationparameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0). The WTRU maytransmit SRS for each additional configured antenna, in each of the nextWTRU-specific subframes.

As an alternative to the WTRU transmitting the SRS for the antennas insequence, the antenna for which the WTRU transmits SRS may be inaccordance with a predefined pattern, for example, based on frequencyhopping parameters, (similar to LTE R8).

As an alternative to transmitting in every cell-specific subframe orWTRU-specific subframe, the WTRU may transmit SRS in every Nthcell-specific subframe or WTRU-specific subframe.

Described herein are series and parallel transmission schemes that maybe used for SRS transmissions on multiple antennas. The schemes mayinclude 1) parallel transmissions where all SRS transmissions are in thesame subframe; 2) series transmissions where all SRS transmissions arein different subframes, such as in sequence or according to a predefinedpattern based on for example, frequency hopping parameters; or 3) eitherparallel or series transmissions based on a given criteria such aspathloss. Selection of parallel or series transmission may be determinedby the network, (i.e., the base station) or the WTRU.

Described herein are methods for determining or switching thetransmission scheme. In a first solution, the base station may decideand inform the WTRU what to do. The network may determine the SRStransmission scheme, (series or parallel), and send an indication to theWTRU to tell it which transmission scheme to use. Upon receipt of theindication from the base station, the WTRU may set its SRS transmissionscheme to series or parallel as requested and transmit accordingly inthe next subframe in which it will transmit SRS. Alternatively, themessage may explicitly identify the time at which the change occurs and,in this case, the WTRU may use the time explicitly defined. Theindication from the base station may be included in a DCI format such asan UL grant. The indication may be included in the trigger for aperiodicSRS. The indication may be included in higher layer signaling such as anRRC message from the base station.

In a second solution, the WTRU may make a decision as to a transmissionscheme and the WTRU or a base station may control the selection of thetransmission scheme. In one variation, the WTRU may determine itspreferred SRS transmission scheme, (series or parallel) and send anindication to the network to tell it which transmission scheme itprefers. The indication of the preferred scheme may be an explicitindication of preferred scheme, (i.e., series or parallel) or otherindication(s) of WTRU status, (such as power headroom, an alert ofreaching maximum power, and the like) which implies the preferredscheme. In response to the indication from the WTRU, the base stationmay send an indication to the WTRU to use a different transmissionscheme, such as to change from a parallel scheme to a series scheme. Theindication from the base station may be included in a DCI format such asan UL grant, in the trigger for aperiodic SRS or in higher layersignaling such as an RRC message from the base station.

Upon receipt of the indication from the base station, the WTRU may setits SRS transmission scheme to series or parallel as requested andtransmit accordingly in, for example, the next subframe in which ittransmits SRS. Alternatively, the message/indication from the basestation may explicitly identify the time at which the change occurs and,in this case the WTRU may use the time explicitly defined.

Thresholding may be used such that the WTRU informs the base station ofa newly preferred scheme after the newly preferred scheme remains thepreferred scheme for some amount of time or for some number of SRStransmissions.

In another variation of the second solution, the WTRU may determine itspreferred SRS transmission scheme (series or parallel). The preferredtransmission scheme may be based on the WTRU's determination of requiredpower for SRS transmission using its current SRS transmission scheme orusing SRS parallel transmission scheme. The basic premise is that it ispreferred to have the WTRU transmit in parallel and that it switches toseries if and only if parallel operation requires more than thepermitted power, based on the WTRU's ratings.

The WTRU may determine if parallel transmission is supportable. If not,it notifies the network, (for example, the base station). If the WTRU isalready in the series transmission mode, then, it may continue to testto see if it can return to parallel transmission mode and may notify thenetwork when it determines that it can.

There are several approaches for interoperating with the base station.The WTRU may announce that it will switch and switches at a predefinedtime. Alternatively, the WTRU may announce that it will switch and waitfor an acknowledgement from the base station before switching.Alternatively, the WTRU may announce that it recommends a switch andsends a message to the base station. The base station may send aresponse that confirms the change, (or it may not). The WTRU may waitfor the message from the base station to switch, and, if it gets themessage, it may switch at the designated time. The designated time maybe implied, e.g., a fixed defined time after the message. Alternatively,it may be defined explicitly in the message from the base station to theWTRU.

Described herein are examples that may use the above selection orswitching approaches with respect to parallel and series transmissionschemes. In an example, while using the SRS parallel transmissionscheme, the WTRU may determine whether or not transmission of all itsantennas in parallel, (i.e., in one symbol of one subframe), wouldresult in exceeding maximum power, (before employing power reductiontechniques to avoid exceeding maximum power). If the WTRU determinesthat it will exceed maximum power, the WTRU may send an indication tothe network to inform it of the situation. The indication may beincluded in an RRC message, a MAC control element, or physical layersignaling, and may be a single bit, a headroom value, or otherindication. The base station may subsequently send an indication to theWTRU to switch to series transmission.

In another example, while using the SRS series transmission scheme, theWTRU may determine whether or not transmission of all its antennas inparallel, (i.e., in one symbol of one subframe), would result inexceeding maximum power, (before employing power reduction techniques toavoid exceeding maximum power). If the WTRU determines that it will notexceed maximum power, the WTRU may send an indication to the network toinform it of the situation. The indication may be included in an RRCmessage, a MAC control element, or physical layer signaling, and may bea single bit, a headroom value, or other indication. The base stationmay subsequently send an indication to the WTRU to switch to paralleltransmission.

In another example, while using the SRS parallel transmission scheme,the WTRU may determine whether or not transmission of all its antennasin parallel, (i.e., in one symbol of one subframe), would result inexceeding maximum power, (before employing power reduction techniques toavoid exceeding maximum power). If the WTRU determines that it willexceed maximum power, the WTRU may send an indication to the network toinform it that the WTRU will switch to SRS series transmission scheme.The indication may be included in an RRC message, a MAC control element,or physical layer signaling, and may be a single bit, a headroom value,or other indication. The WTRU may then set its SRS transmission schemeto series and begin using series transmission at a predefined time afterit sent the change indication to the base station, such as foursubframes later.

In another example, while using the SRS series transmission scheme, theWTRU may determine whether or not transmission of all its antennas inparallel, (i.e., in one symbol of one subframe), would result inexceeding maximum power, (before employing power reduction techniques toavoid exceeding maximum power). If the WTRU determines that it will notexceed maximum power, the WTRU may send an indication to the network toinform it that the WTRU will switch to SRS parallel transmission scheme.The indication may be included in an RRC message, a MAC control element,or physical layer signaling, and may be a single bit, a headroom value,or other indication. The WTRU may then set its SRS transmission schemeto parallel and begin using parallel transmission at a predefined timeafter it sent the change indication to the base station, such as foursubframes later.

In all cases, thresholding may be used such that the WTRU may inform thebase station of a newly preferred scheme after the newly preferredscheme remains the preferred scheme for some amount of time or for somenumber of SRS transmissions.

Described herein are methods for using the SRS transmission schemes. Inan example configuration method, the subframes that may be used for SRSparallel transmission schemes and SRS series transmission schemes may bethe same subframes, i.e., a WTRU may receive a configuration from thebase station to use for both series and parallel transmission schemes.For example, the WTRU may receive an SRS configuration index into theSRS configuration table, (e.g., the same one as that used for LTE R8WTRU-specific SRS or a similar one), that provides a subframeperiodicity T_(SRS) and subframe offset T_(offset) to be used for bothparallel and series transmission schemes.

The WTRU may receive a cyclic shift and/or transmission comb for oneantenna from the base station. The WTRU may receive a separate cyclicshift and transmission comb for each antenna or the WTRU may derive thecyclic shift and/or transmission comb for each additional antenna fromthe cyclic shift and/or transmission comb of the first antenna.Derivation may be in accordance with one of the methods provided earlierherein.

The WTRU may receive additional transmission parameters from the basestation such as those defined in the SoundingRS-UL-ConfigDedicated.These SRS transmission parameters such as the frequency hoppingparameters, may be the same or different for the different antennas. Foraperiodic SRS, duration meaning single or infinite may be unnecessary ormay be replaced by a duration meaning the number of subframes in whichto transmit SRS (for multi-shot).

In a second configuration method, when the parallel SRS transmissionscheme is used, given the transmission subframes and the transmissionparameters for the antennas, upon receipt of a trigger or whiletransmission is activated, the WTRU may transmit on all its antennassimultaneously using the configured parameters in the appropriatesubframe(s) according to the trigger or activation to transmission rulessuch as those described herein.

When the series SRS transmission scheme is used, given the transmissionsubframes and the transmission parameters for the antennas, upon receiptof a trigger or while transmission is activated, the WTRU may transmiton one antenna in each of the subframes according to the trigger oractivation to transmission rules such as those described herein. Foreach SRS transmission on a particular antenna, the WTRU may use theconfigured parameters for that antenna. Alternatively, for each SRStransmission on a particular antenna, the WTRU may use the configuredparameters for the first antenna.

Described herein are methods for using parallel transmission schemes.For the parallel SRS transmission scheme for the case where a triggerresults in a single transmission, given a trigger in subframe n, theWTRU may transmit SRS for all its antennas simultaneously in one of thesubsequent subframes based on one of the following rules. In accordancewith a rule, the WTRU may transmit in the next subframe (n+1). Inaccordance with another rule, it may transmit in the next cell-specificsubframe, (for example, subframe ‘k_(SRS)’ such that k_(SRS)>=n+1 andalso satisfies the cell-specific SRS subframe offset and SRS periodicityconfiguration parameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC)).

In accordance with another rule, the WTRU may transmit in the nextWTRU-specific subframe, (for example for FDD, subframe ‘k_(SRS)’ suchthat k_(SRS)>=n+1 and also satisfies the WTRU-specific SRS subframeoffset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0). These WTRU-specificsubframes for aperiodic SRS may be the same as or different from thoseconfigured for periodic SRS transmission.

In accordance with another rule, the WTRU may transmit in the next cellspecific subframe at least four subframes after the triggering subframe,(for example, subframe ‘k_(SRS)’ such that k_(SRS)>=n+4 and alsosatisfies the cell-specific SRS subframe offset and SRS periodicityconfiguration parameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC)).

In accordance with another rule, the WTRU may transmit in the nextWTRU-specific subframe at least four subframes after the triggeringsubframe, (for example, for FDD, subframe ‘k_(SRS)’ such thatk_(SRS)>=n+4 and also satisfies the WTRU-specific SRS subframe offsetand SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0). These WTRU-specificsubframes for aperiodic SRS may be the same as or different from thoseconfigured for periodic SRS transmission.

For the parallel SRS transmission scheme for the case where a triggermay result in multiple transmissions (i.e., multi-shot SRStransmission), given a duration of Ns subframes for transmission and atrigger in subframe n, the WTRU may transmit SRS for all of its antennassimultaneously in Ns subframes according to one of the following rules.In accordance with a rule, the WTRU may transmit in each of the next Nssubframes where the starting subframe is subframe n+1. In accordancewith another rule, the WTRU may transmit in each of the next Nscell-specific subframes where, for example, each subframe ‘k_(SRS)’ issuch that k_(SRS)>=n+1 and also satisfies the cell-specific SRS subframeoffset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC).

In accordance with another rule, the WTRU may transmit in each of thenext Ns WTRU-specific subframes where, for example, for FDD, eachsubframe ‘k_(SRS)’ is such that k_(SRS)>=n+1 and also satisfies theWTRU-specific SRS subframe offset and SRS periodicity configurationparameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. TheseWTRU-specific subframes may be the same as or different from thoseconfigured for periodic SRS transmission.

In accordance with another rule, the WTRU may transmit in each of thenext Ns cell specific subframes at least four subframes after thetriggering subframe, where, for example, for FDD, each subframe‘k_(SRS)’ is such that k_(SRS)>=n+4 and also satisfies the cell-specificSRS subframe offset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC).

In accordance with another rule, the WTRU may transmit in each of thenext Ns WTRU-specific subframes at least four subframes after thetriggering subframe, where, for example for FDD, each subframe ‘k_(SRS)’is such that k_(SRS)>=n+4 and also satisfies the WTRU-specific SRSsubframe offset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset)) modT_(SRS)=0. These WTRU-specificsubframes may be the same as or different from those configured forperiodic SRS transmission.

A value of Ns=1 may be used to indicate a duration of one subframe. Inthis case a trigger would result in SRS transmission on all antennas inone subframe which is the same as the single transmission case. Apredefined value of Ns may be used to indicate continuous transmissionor periodic transmission.

As an alternative to transmitting in every subframe, cell-specificsubframe, or WTRU-specific subframe, the WTRU may transmit SRS in everyNth subframe, cell-specific subframe, or WTRU-specific subframe.

For the parallel SRS transmission scheme when activation/deactivation isused, given a trigger (activation) in subframe n, the WTRU may transmitSRS for all its antennas simultaneously according to one of thefollowing rules. In accordance with a rule, the WTRU may transmit ineach of the next subframes beginning with subframe n+1, untildeactivation. In accordance with another rule, the WTRU may transmit ineach of the next cell-specific subframes until deactivation, where, forexample, each subframe ‘k_(SRS)’ is such that k_(SRS)>=n+1 and alsosatisfies the cell-specific SRS subframe offset and SRS periodicityconfiguration parameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC).

In accordance with another rule, the WTRU may transmit in each of thenext WTRU-specific subframes until deactivation, where, for example forFDD, each subframe ‘k_(SRS)’ is such that k_(SRS)>=n+1 and alsosatisfies the WTRU-specific SRS subframe offset and SRS periodicityconfiguration parameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0.These WTRU-specific subframes may be the same as or different from thoseconfigured for periodic SRS transmission.

In accordance with another rule, the WTRU may transmit in each of thenext cell specific subframes at least four subframes after thetriggering subframe until deactivation, where, for example for FDD, eachsubframe ‘k_(SRS)’ is such that k_(SRS)>=n+4 and also satisfies thecell-specific SRS subframe offset and SRS periodicity configurationparameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC).

In accordance with another rule, the WTRU may transmit in each of thenext WTRU-specific subframes at least four subframes after thetriggering subframe until deactivation, where, for example for FDD, eachsubframe ‘k_(SRS)’ is such that k_(SRS)>=n+4 and also satisfies theWTRU-specific SRS subframe offset and SRS periodicity configurationparameters (10·n_(f)+k_(SRS)−T_(offset)) modT_(SRS)=0. TheseWTRU-specific subframes may be the same as or different from thoseconfigured for periodic SRS transmission.

As an alternative to transmitting in every subframe, cell-specificsubframe, or WTRU-specific subframe, the WTRU may transmit SRS in everyNth subframe, cell-specific subframe, or WTRU-specific subframe.

Described herein are methods for using series transmission schemes. Forthe series SRS transmission scheme using one antenna at a time, given atrigger in subframe n, the WTRU may transmit SRS for one of its antennasbased on one of the following rules. In accordance with a rule, the WTRUmay transmit in the next subframe (n+1). In accordance with anotherrule, it may transmit in the next cell-specific subframe (for example,subframe ‘k_(SRS)’ such that k_(SRS)>=n+1 and also satisfies thecell-specific SRS subframe offset and SRS periodicity configurationparameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC)).

In accordance with another rule, the WTRU may transmit in the nextWTRU-specific subframe, (for example for FDD, subframe ‘k_(SRS)’ suchthat k_(SRS)>=n+1 and also satisfies the WTRU-specific SRS subframeoffset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0). These WTRU-specificsubframes for aperiodic SRS may be the same as or different from thoseconfigured for periodic SRS transmission.

In accordance with another rule, the WTRU may transmit in the next cellspecific subframe at least four subframes after the triggering subframe,(for example, subframe ‘k_(SRS)’ such that k_(SRS)>=n+4 and alsosatisfies the cell-specific SRS subframe offset and SRS periodicityconfiguration parameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC)).

In accordance with another rule, the WTRU may transmit in the nextWTRU-specific subframe at least four subframes after the triggeringsubframe, (for example for FDD, subframe ‘k_(SRS)’ such thatk_(SRS)>=n+4 and also satisfies the WTRU-specific SRS subframe offsetand SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0) These WTRU-specific subframesfor aperiodic SRS may be the same as or different from those configuredfor periodic SRS transmission.

SRS for the different antennas may be transmitted in sequence (onetransmission on one antenna per trigger) such that it is unambiguous tothe WTRU and the base station as to which antenna is being used for SRStransmission in a given subframe.

As an alternative to the WTRU transmitting the SRS for the antennas insequence, the antenna for which the WTRU may transmit SRS may be inaccordance with a predefined pattern. For example, it may be based onthe frequency hopping parameters, (such as in LTE R8).

For the single transmission, all antennas in sequence series SRStransmission scheme, given a trigger in subframe n, the WTRU maytransmit SRS for its Na antennas in sequence, one at a time (one persubframe) according to one of the following rules. The WTRU may transmitSRS for one of the Na antennas, (cycling through them in sequence), ineach of the next Na subframes where the starting subframe is subframen+1. In accordance with another rule, the WTRU may transmit SRS for oneof the Na antennas, (cycling through them in sequence), in each of thenext Na cell-specific subframes where for example each subframe‘k_(SRS)’ is such that k_(SRS)>=n+1 and also satisfies the cell-specificSRS subframe offset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC).

In accordance with another rule, the WTRU may transmit SRS for one ofthe Na antennas, (cycling through them in sequence), in each of the nextNa WTRU-specific subframes where, for example for FDD, each subframe‘k_(SRS)’ is such that k_(SRS)>=n+1 and also satisfies the WTRU-specificSRS subframe offset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. These WTRU-specific subframesmay be the same as or different from those configured for periodic SRStransmission.

In accordance with another rule, the WTRU may transmit SRS for one ofthe Na antennas, (cycling through them in sequence), in each of the nextNa cell-specific subframes at least four subframes after the triggeringsubframe, where, for example, each subframe ‘k_(SRS)’ is such thatk_(SRS)>=n+4 and also satisfies the cell-specific SRS subframe offsetand SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC).

In accordance with another rule, the WTRU may transmit SRS for one ofthe Na antennas, (cycling through them in sequence), in each of the nextNa WTRU-specific subframes at least four subframes after the triggeringsubframe, where, for example, for FDD, each subframe ‘k_(SRS)’ is suchthat k_(SRS)>=n+4 and also satisfies the WTRU-specific SRS subframeoffset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. These WTRU-specific subframesmay be the same as or different from those configured for periodic SRStransmission.

As an alternative to the WTRU transmitting the SRS for the antennas insequence, the antenna for which the WTRU transmits SRS may be inaccordance with a predefined pattern. For example, based on thefrequency hopping parameters, (such as for LTE R8).

As an alternative to transmitting in every subframe, cell-specificsubframe, or WTRU-specific subframe, WTRU may transmit SRS in every Nthsubframe, cell-specific subframe, or WTRU-specific subframe.

For the multiple transmission, all antennas in sequence series SRStransmission scheme and a duration of Ns subframes for transmission,given a trigger in subframe n, the WTRU may transmit SRS for its Naantennas in sequence, one at a time (one per subframe) according to oneof the following rules for aperiodic SRS transmission. The WTRU maytransmit SRS for one of the Na antennas, (cycling through them insequence), in each of the next Ns subframes where the starting subframeis subframe n+1. In accordance with another rule, the WTRU may transmitSRS for one of the Na antennas, (cycling through them in sequence), ineach of the next Ns cell-specific subframes where, for example, eachsubframe ‘k_(SRS)’ is such that k_(SRS)>=n+1 and also satisfies thecell-specific SRS subframe offset and SRS periodicity configurationparameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC).

In accordance with another rule, the WTRU may transmit SRS for one ofthe Na antennas, (cycling through them in sequence), in each of the nextNs WTRU-specific subframes where, for example, for FDD, each subframe‘k_(SRS)’ is such that k_(SRS)>=n+1 and also satisfies the WTRU-specificSRS subframe offset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. These WTRU-specific subframesmay be the same as or different from those configured for periodic SRStransmission.

In accordance with another rule, the WTRU may transmit SRS for one ofthe Na antennas, (cycling through them in sequence), in each of the nextNs cell specific subframes at least four subframes after the triggeringsubframe, where, for example, each subframe ‘k_(SRS)’ is such thatk_(SRS)>=n+4 and also satisfies the cell-specific SRS subframe offsetand SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC).

In accordance with another rule, the WTRU may transmit SRS for one ofthe Na antennas, (cycling through them in sequence), in each of the nextNs WTRU-specific subframes at least four subframes after the triggeringsubframe, where, for example for FDD, each subframe ‘k_(SRS)’ is suchthat k_(SRS)>=n+4 and also satisfies the WTRU-specific SRS subframeoffset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. These WTRU-specific subframesmay be the same as or different from those configured for periodic SRStransmission.

A value of Ns=1 may be used to indicate a duration of one subframe. Inthis case a trigger would result in SRS transmission of one antenna inone subframe, which is the same as the single transmission case. Apredefined value of Ns may be used to indicate continuous transmissionor periodic transmission.

As an alternative to the WTRU transmitting the SRS for the antennas insequence, the antenna for which the WTRU may transmit SRS may be inaccordance with a predefined pattern. For example, based on thefrequency hopping parameters (such as in LTE R8).

As an alternative to transmitting in every subframe, cell-specificsubframe, or WTRU-specific subframe, the WTRU may transmit SRS in everyNth subframe, cell-specific subframe, or WTRU-specific subframe.

In another solution for the multiple transmission, all antennas insequence, series SRS transmission scheme and a duration of Ns subframesfor transmission, given a trigger in subframe n, the WTRU may transmitSRS for its Na antennas in sequence, one at a time (one per subframe)according to one of the following rules. The WTRU may transmit SRS forone of the Na antennas, (cycling through them in sequence), in each ofthe next Na×Ns subframes where the starting subframe is subframe n+1. Inaccordance with another rule, the WTRU may transmit SRS for one of theNa antennas, (cycling through them in sequence), in each of the nextNa×Ns cell-specific subframes where, for example, each subframe‘k_(SRS)’ is such that k_(SRS)>=n+1 and also satisfies the cell-specificSRS subframe offset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC).

The WTRU may transmit SRS for one of the Na antennas, (cycling throughthem in sequence), in each of the next Na×Ns WTRU-specific subframeswhere, for example, for FDD, each subframe ‘k_(SRS)’ is such thatk_(SRS)>=n+1 and also satisfies the WTRU-specific SRS subframe offsetand SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. These WTRU-specific subframesmay be the same as or different from those configured for periodic SRStransmission.

The WTRU may transmit SRS for one of the Na antennas, (cycling throughthem in sequence), in each of the next Na×Ns cell specific subframes atleast four subframes after the triggering subframe, where, for example,each subframe ‘k_(SRS)’ is such that k_(SRS)>=n+4 and also satisfies thecell-specific SRS subframe offset and SRS periodicity configurationparameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC).

The WTRU may transmit SRS for one of the Na antennas, (cycling throughthem in sequence), in each of the next Na×Ns WTRU-specific subframes atleast four subframes after the triggering subframe, where, for example,for FDD, each subframe ‘k_(SRS)’ is such that k_(SRS)>=n+4 and alsosatisfies the WTRU-specific SRS subframe offset and SRS periodicityconfiguration parameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0.These WTRU-specific subframes may be the same as or different from thoseconfigured for periodic SRS transmission.

A value of Ns=1 may be used to indicate a duration of one subframe. Inthis case a trigger would result in SRS transmission in Na×1=Nasubframes. A predefined value of Ns may be used to indicate continuoustransmission or periodic transmission.

As an alternative to the WTRU transmitting the SRS for the antennas insequence, the antenna for which the WTRU may transmit SRS may beaccording to a predefined pattern. For example, it may be based on thefrequency hopping parameters, (such as in LTE R8).

As an alternative to transmitting in every subframe, cell-specificsubframe, or WTRU-specific subframe, WTRU may transmit SRS in every Nthsubframe, cell-specific subframe, or WTRU-specific subframe.

For the series SRS transmission scheme when activation/deactivation isused, given a trigger (activation) in subframe n, the WTRU may transmitSRS for its Na antennas in sequence, one at a time (one per subframe)according to one of the following rules. The WTRU may transmit SRS forone of the Na antennas, (cycling through them in sequence), in each ofthe next subframes beginning with subframe n+1, until deactivation. Inaccordance with another rule, the WTRU may transmit SRS for one of theNa antennas, (cycling through them in sequence), in each of the nextcell-specific subframes where for example each subframe ‘k_(SRS)’ issuch that k_(SRS)>=n+1 and also satisfies the cell-specific SRS subframeoffset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC), until deactivation.

In accordance with another rule, the WTRU may transmit SRS for one ofthe Na antennas, (cycling through them in sequence), in each of the nextWTRU-specific subframes where, for example for FDD, each subframe‘k_(SRS)’ is such that k_(SRS)>=n+1 and also satisfies the WTRU-specificSRS subframe offset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. These WTRU-specific subframesmay be the same as or different from those configured for periodic SRStransmission, until deactivation.

In accordance with another rule, the WTRU may transmit SRS for one ofthe Na antennas, (cycling through them in sequence), in each of the nextcell specific subframes at least four subframes after the triggeringsubframe, where, for example, each subframe ‘k_(SRS)’ is such thatk_(SRS)>=n+4 and also satisfies the cell-specific SRS subframe offsetand SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC), until deactivation.

In accordance with another rule, the WTRU may transmit SRS for one ofthe Na antennas, (cycling through them in sequence), in each of the nextWTRU-specific subframes at least four subframes after the triggeringsubframe, where, for example, for FDD, each subframe ‘k_(SRS)’ is suchthat k_(SRS)>=n+4 and also satisfies the WTRU-specific SRS subframeoffset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. These WTRU-specific subframesmay be the same as or different from those configured for periodic SRStransmission.

As an alternative to the WTRU transmitting the SRS for the antennas insequence, the antenna for which the WTRU may transmit SRS may beaccording to a predefined pattern. For example, it may be based on thefrequency hopping parameters, (such as in LTE R8).

As an alternative to transmitting in every subframe, cell-specificsubframe, or WTRU-specific subframe, WTRU may transmit SRS in every Nthsubframe, cell-specific subframe, or WTRU-specific subframe.

Described herein are methods for SRS Transmission on fewer antennas thanavailable. Given a WTRU with Na antennas, the WTRU may receiveconfiguration or indication from the base station to use fewer than itsNa antennas when transmitting SRS. An LTE-A WTRU with multiple transmitantennas may have two modes of operation, Multiple Antenna Port Mode(MAPM) and Single Antenna Port Mode (SAPM), where a default mode ofoperation may be SAPM.

For MAPM, whether or not to use fewer antennas than Na when transmittingSRS may be signaled to the WTRU by the base station via physical layeror higher layer signaling. Alternatively, use of fewer than Na antennasfor SRS may be predefined. For example, it may be defined that themaximum number of antennas to use for SRS is two.

When operating in MAPM, the WTRU may interpret use of fewer antennasthan Na, for example, use of Nb antennas where Nb<Na, to mean operateaccording to the rules defined for SRS with multiple antennas such asdescribed herein, but using Nb antennas instead of Na.

For SAPM, the WTRU may transmit SRS according to the LTE R8specification. If the WTRU has parameters configured for SRS for MAPM,upon switching to SAPM, if not reconfigured, the WTRU may use theconfigured parameters for antenna 1 as its WTRU-specific parameters forSRS transmission in SAPM.

Described herein are methods for handling multiple SRS transmissionsresulting from a single trigger (multi-shot transmission). SRStransmission in multiple subframes may be useful for improvedmeasurement performance or for different antennas. SRS transmission inmultiple subframes may also be useful for supporting frequency hopping.Given that a trigger may result in more than one SRS transmission,transmission in consecutive subframes may be considered. This may,however present a problem in that unless all subframes are cell-specificsubframes, which are subframes in which no WTRU in the cell is permittedto transmit data in the symbol used for SRS, transmission in consecutivesubframes may cause excessive interference among WTRUs transmitting SRSand WTRUs transmitting data. In the case all subframes are cell-specificsubframes, the last symbol of data will be punctured by all WTRUstransmitting in the cell which may result in reduced performance orreduced capacity. The methods described, in part, provide a means formulti-shot SRS transmission that reduces the potential for interferenceand the need to puncture the last symbol in every subframe.

Described herein is a solution for managing the use of multiple and/orsingle transmissions in response to a trigger. In an example, a triggermay command Ns SRS transmissions, (Ns may be 1 or more). In anotherexample, the network may select a value for Ns between 1 and Nmax andassign this value. This value may be a system parameter, a cell-specificparameter, or a WTRU-specific parameter, signaled to the WTRU by thebase station. An aperiodic SRS trigger may include the value of Ns. Thismay require more bits to support the additional information.Alternatively, the value of Ns may be provided by higher layersignaling.

In another solution, let Ns be the number of SRS transmissions to occuras the result of one SRS trigger. Given a trigger, the WTRU may transmitSRS in the next cell-specific subframe and then in each of the next Ns-1cell specific subframes. For example for FDD, given an SRS trigger insubframe ‘n’ the WTRU may transmit SRS (starting) in subframe ‘k_(SRS)’such that k_(SRS)>=n+1 and also satisfies the cell-specific SRS subframeoffset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC). This first SRS transmission is thenfollowed by an SRS transmission in each of the next Ns-1 subframes(after subframe k_(SRS)) that satisfy the cell-specific SRS subframeoffset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC). As an alternative to transmitting in everycell-specific subframe, WTRU may transmit SRS in every Nth cell-specificsubframe.

For the case where SRS activation/deactivation may be used as opposed toa trigger resulting in a fixed number of SRS transmissions, in responseto the activation, the WTRU may transmit SRS in the next cell-specificsubframe and then in each of the next cell specific subframes untildeactivation. Upon deactivation, the WTRU may stop transmitting SRS.Note that activation may be viewed as a type of trigger. For example forFDD, given an SRS activation in subframe ‘n’ the WTRU may transmit SRS(starting) in subframe ‘k_(SRS)’ such that k_(SRS)>=n+1 and alsosatisfies the cell-specific SRS subframe offset and SRS periodicityconfiguration parameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC). This first SRStransmission is then followed by an SRS transmission in each of the nextsubframes (after subframe k_(SRS)) that satisfy the cell-specific SRSsubframe offset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC). Upon deactivation, the WTRU may stoptransmitting SRS. As an alternative to transmitting in everycell-specific subframe, WTRU may transmit SRS in every Nth cell-specificsubframe.

The above solutions may be extended to the multiple antenna case. Forthe multiple antenna case, given a trigger, the WTRU may transmit SRS inthe next cell-specific subframe and then in each of the next Ns-1 cellspecific subframes. SRS may be transmitted for all antennas in the samesubframe. In this case orthogonality may be achieved by cyclic shiftmultiplexing and/or different comb assignments. Alternatively, SRS maybe transmitted for the different configured antennas such thattransmission alternates among (cycles through) the configured antennasin each of the Ns subframes. As an alternative to the WTRU transmittingthe SRS for the antennas in sequence, the antenna for which the WTRUtransmits SRS may be in accordance with a predefined pattern. Forexample, it may be based on the frequency hopping parameters, (such asin LTE R8). As an alternative to transmitting in every cell-specificsubframe, the WTRU may transmit SRS in every Nth cell-specific subframe.

For the multiple antenna case, where SRS activation/deactivation may beused, the WTRU may transmit SRS in the next cell-specific subframe andthen in each of the next cell specific subframes until deactivation. SRSmay be transmitted for all antennas in the same subframe. In this case,orthogonality may be achieved by cyclic shift multiplexing and/ordifferent comb assignments. Alternatively, SRS may be transmitted forthe different configured antennas such that transmission alternatesamong (cycles through) the configured antennas in each of the cellspecific subframes until deactivation. As an alternative to the WTRUtransmitting the SRS for the antennas in sequence, the antenna for whichthe WTRU may transmit SRS may be in accordance with a predefinedpattern. For example, it may be based on the frequency hoppingparameters, (such as in LTE R8). As an alternative to transmitting inevery cell-specific subframe, WTRU may transmit SRS in every Nthcell-specific subframe.

In another solution for handling multiple transmission, let Ns be thenumber of SRS transmissions to occur as the result of one SRS trigger.Given a trigger in subframe n, the WTRU may transmit SRS in the nextcell-specific subframe that is at least 4 subframes after the triggeringsubframe n (i.e., n+4 or later) and then in each of the next Ns-1 cellspecific subframes. For example for FDD, given an SRS trigger insubframe ‘n’ the WTRU may transmit SRS (starting) in subframe ‘k_(SRS)’such that k_(SRS)>=n+4 and also satisfies the cell-specific SRS subframeoffset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC). This first SRS transmission is thenfollowed by an SRS transmission in each of the next Ns-1 subframes(after subframe k_(SRS)) that satisfy the cell-specific SRS subframeoffset and SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC). As an alternative to transmitting in everycell-specific subframe, the WTRU may transmit SRS in every Nthcell-specific subframe.

For the case where SRS activation/deactivation may be used as opposed toa trigger resulting in a fixed number of SRS transmissions, in responseto the activation, the WTRU may transmit SRS in the next cell-specificsubframe that is at least four subframes after the triggering subframen, (i.e., n+4 or later) and then in each of the next cell specificsubframes until deactivation. Upon deactivation, the WTRU may stoptransmitting SRS. Activation/deactivation may be viewed as a type oftrigger. For example for FDD, given an SRS activation in subframe ‘n’the WTRU may transmit SRS (starting) in subframe ‘k_(SRS)’ such thatk_(SRS)>=n+4 and also satisfies the cell-specific SRS subframe offsetand SRS periodicity configuration parameters└n_(s)/2┘modT_(SFC)∈Δ_(SFC). This first SRS transmission may then befollowed by an SRS transmission in each of the next subframes (aftersubframe k_(SRS)) that satisfy the cell-specific SRS subframe offset andSRS periodicity configuration parameters └n_(s)/2┘modT_(SFC)∈Δ_(SFC).Upon deactivation, the WTRU may stop transmitting SRS. As an alternativeto transmitting in every cell-specific subframe, WTRU may transmit SRSin every Nth cell-specific subframe.

The above two examples may be extended to the multiple antenna case.Given a trigger in subframe n, the WTRU may transmit SRS in the nextcell-specific subframe that is at least four subframes after thetriggering subframe n, (i.e., n+4 or later), and then in each of thenext Ns-1 cell specific subframes. SRS may be transmitted for allantennas in the same subframe. In this case, orthogonality may beachieved by cyclic shift multiplexing and/or different comb assignments.Alternatively, SRS may be transmitted for the different configuredantennas such that transmission alternates among (cycles through) theconfigured antennas in each of the Ns subframes. As an alternative tothe WTRU transmitting the SRS for the antennas in sequence, the antennafor which the WTRU transmits SRS may be in accordance with a predefinedpattern. For example, it may be based on the frequency hoppingparameters, (such as in LTE R8). As an alternative to transmitting inevery cell-specific subframe, the WTRU may transmit SRS in every Nthcell-specific subframe.

The activation/deactivation case may also be extended to the multipleantenna case. Given a trigger (activation) in subframe n, the WTRU maytransmit SRS in the next cell-specific subframe that is at least foursubframes after the triggering subframe n (i.e., n+4 or later) and thenin each of the next cell specific subframes until deactivation. SRS maybe transmitted for all antennas in the same subframe. In this caseorthogonality may be achieved by cyclic shift multiplexing and/ordifferent comb assignments. Alternatively, SRS may be transmitted forthe different configured antennas such that transmission alternatesamong (cycles through) the configured antennas in each of the cellspecific subframes until deactivation. As an alternative to the WTRUtransmitting the SRS for the antennas in sequence, the antenna for whichthe WTRU transmits SRS may be according to a predefined pattern. Forexample, it may be based on the frequency hopping parameters, (such asin LTE R8). As an alternative to transmitting in every cell-specificsubframe, the WTRU may transmit SRS in every Nth cell-specific subframe.

In another solution for handling multiple transmissions, let Ns be thenumber of SRS transmissions to occur as the result of one SRS trigger.Given a trigger, the WTRU may transmit SRS in the next WTRU-specificsubframe and then in each of the next Ns-1 WTRU-specific subframes. Forexample for FDD, given an SRS trigger in subframe ‘n’ the WTRU maytransmit SRS (starting) in subframe ‘k_(SRS)’ such that k_(SRS)>=n+1 andalso satisfies the WTRU-specific SRS subframe offset and SRS periodicityconfiguration parameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. Thisfirst SRS transmission may then be followed by an SRS transmission ineach of the next Ns-1 subframes (after subframe k_(SRS)) that satisfythe WTRU-specific SRS subframe offset and SRS periodicity configurationparameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. As an alternativeto transmitting in every WTRU-specific subframe, the WTRU may transmitSRS in every Nth WTRU-specific subframe.

For the case where SRS activation/deactivation may be used as opposed toa trigger resulting in a fixed number of SRS transmissions, in responseto the activation, the WTRU may transmit SRS in the next WTRU-specificsubframe and then in each of the next WTRU-specific subframes untildeactivation. Upon deactivation, the WTRU stops transmitting SRS.Activation may be viewed as a type of trigger. For example for FDD,given an SRS activation in subframe ‘n’ the WTRU may transmit SRS(starting) in subframe ‘k_(SRS)’ such that k_(SRS)>=n+1 and alsosatisfies the WTRU-specific SRS subframe offset and SRS periodicityconfiguration parameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. Thisfirst SRS transmission is then followed by an SRS transmission in eachof the next subframes (after subframe k_(SRS)) that satisfy theWTRU-specific SRS subframe offset and SRS periodicity configurationparameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. Upon deactivation,the WTRU may stop transmitting SRS. As an alternative to transmitting inevery WTRU-specific subframe, the WTRU may transmit SRS in every NthWTRU-specific subframe.

In the two preceding solutions, the WTRU-specific subframes may be thesame as those defined for LTE R8 periodic SRS or they may be defined bya new configuration provided by the network to the WTRU for aperiodicSRS. For the solutions given above, if a new aperiodic SRS configurationis used, it is assumed that periodicity and offset parameters may beprovided as they are for periodic SRS.

The above solutions may be extended to the multiple antenna case. Forthe multiple antenna case, given a trigger, the WTRU may transmit SRS inthe next WTRU-specific subframe and then in each of the next Ns-1WTRU-specific subframes. SRS may be transmitted for all antennas in thesame subframe. In this case, orthogonality may be achieved by cyclicshift multiplexing and/or different comb assignments. Alternatively, SRSmay be transmitted for the different configured antennas such thattransmission alternates among (cycles through) the configured antennasin each of the Ns subframes. As an alternative to the WTRU transmittingthe SRS for the antennas in sequence, the antenna for which the WTRUtransmits SRS may be in accordance with a predefined pattern. Forexample, it may be based on the frequency hopping parameters, (such asin LTE R8/9). As an alternative to transmitting in every WTRU-specificsubframe, the WTRU may transmit SRS in every Nth WTRU-specific subframe.

For the multiple antenna case, where SRS activation/deactivation may beused, the WTRU may transmit SRS in the next WTRU-specific subframe andthen in each of the next WTRU-specific subframes until deactivation. SRSmay be transmitted for all antennas in the same subframe. In this case,orthogonality may be achieved by cyclic shift multiplexing and/ordifferent comb assignments. Alternatively, SRS may be transmitted forthe different configured antennas such that transmission alternatesamong (cycles through) the configured antennas in each of theWTRU-specific subframes until deactivation. As an alternative to theWTRU transmitting the SRS for the antennas in sequence, the antenna forwhich the WTRU may transmit SRS may be in accordance with a predefinedpattern. For example, it may be based on the frequency hoppingparameters, (such as in LTE R8). As an alternative to transmitting inevery WTRU-specific subframe, the WTRU may transmit SRS in every NthWTRU-specific subframe.

The above solutions may be extended to the multiple antenna case inwhich each antenna may have its own antenna-specific subframeconfiguration. In this case, given a trigger, the WTRU may transmit SRSfor each antenna, (that is configured for SRS), in the nextantenna-specific subframe for that antenna and then in each of the nextNs-1 antenna-specific subframes for that antenna. If the subframeparameters are the same for all antennas, SRS may be transmitted for allantennas in the same subframe. In this case orthogonality may beachieved by cyclic shift multiplexing and/or different comb assignments.As an alternative to transmitting in every antenna-specific subframe,the WTRU may transmit SRS in every Nth antenna-specific subframe.

The activation/deactivation solution may be extended to the multipleantenna case in which each antenna has an antenna-specific subframeconfiguration. In this case, given a trigger (activation), the WTRU maytransmit SRS for each antenna, (that is configured for SRS), in the nextantenna-specific subframe for that antenna and then in each of the nextantenna-specific subframes for that antenna until deactivation. If thesubframe parameters are the same for all antennas, SRS may betransmitted for all antennas in the same subframe. In this caseorthogonality may be achieved by cyclic shift multiplexing and/ordifferent comb assignments. As an alternative to transmitting in everyantenna-specific subframe, the WTRU may transmit SRS in every Nthantenna-specific subframe.

In another solution for handling multiple transmissions, let Ns be thenumber of SRS transmissions to occur as the result of one SRS trigger.Given a trigger in subframe n, the WTRU may transmit SRS in the nextWTRU-specific subframe that is at least four subframes after thetriggering subframe n (i.e., n+4 or later) and then in each of the nextNs-1 WTRU-specific subframes. For example for FDD, given an SRS triggerin subframe ‘n’ the WTRU may transmit SRS (starting) in subframe‘k_(SRS)’ such that k_(SRS)>=n+4 and also satisfies the WTRU-specificSRS subframe offset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. This first SRS transmissionmay then be followed by an SRS transmission in each of the next Ns-1subframes (after subframe k_(SRS)) that satisfy the WTRU-specific SRSsubframe offset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. As an alternative totransmitting in every WTRU-specific subframe, the WTRU may transmit SRSin every Nth WTRU-specific subframe.

For the case where SRS activation/deactivation may be used as opposed toa trigger resulting in a fixed number of SRS transmissions, in responseto the activation, the WTRU may transmit SRS in the next WTRU-specificsubframe that is at least four subframes after the triggering subframe n(i.e., n+4 or later) and then in each of the next WTRU-specificsubframes until deactivation. Upon deactivation, the WTRU may stoptransmitting SRS. Activation may be viewed as a type of trigger. Forexample for FDD, given an SRS activation in subframe ‘n’ the WTRU maytransmit SRS (starting) in subframe ‘k_(SRS)’ such that k_(SRS)>=n+4 andalso satisfies the WTRU-specific SRS subframe offset and SRS periodicityconfiguration parameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. Thisfirst SRS transmission may then be followed by an SRS transmission ineach of the next subframes (after subframe k_(SRS)) that satisfy theWTRU-specific SRS subframe offset and SRS periodicity configurationparameters (10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0. Upon deactivation,the WTRU may stop transmitting SRS. As an alternative to transmitting inevery WTRU-specific subframe, the WTRU may transmit SRS in every NthWTRU-specific subframe.

In the above two solutions, the WTRU-specific subframes may be the sameas those defined for LTE R8 periodic SRS or they may be defined byanother configuration provided by the network to the WTRU for aperiodicSRS.

For the solutions presented above, if a new aperiodic SRS configurationis used, it is assumed that periodicity and offset parameters may beprovided as they are for periodic SRS.

The above solutions may be extended to the multiple antenna case. Forthe multiple antenna case, given a trigger in subframe n, the WTRU maytransmit SRS in the next WTRU-specific subframe that is at least foursubframes after the triggering subframe n (i.e., n+4 or later) and thenin each of the next Ns-1 WTRU-specific subframes. SRS may be transmittedfor all antennas in the same subframe. In this case, orthogonality maybe achieved by cyclic shift multiplexing and/or different combassignments. Alternatively, SRS may be transmitted for the differentconfigured antennas such that transmission alternates among (cyclesthrough) the configured antennas in each of the Ns subframes. As analternative to the WTRU transmitting the SRS for the antennas insequence, the antenna for which the WTRU transmits SRS may be inaccordance with a predefined pattern. For example, it may be based onthe frequency hopping parameters, (such as in LTE R8). As an alternativeto transmitting in every WTRU-specific subframe, the WTRU may transmitSRS in every Nth WTRU-specific subframe.

For the multiple antenna case, where SRS activation/deactivation may beused, given a trigger (activation) in subframe n, the WTRU may transmitSRS in the next WTRU-specific subframe that is at least four subframesafter the triggering subframe n (i.e., n+4 or later) and then in each ofthe next WTRU-specific subframes until deactivation. SRS may betransmitted for all antennas in the same subframe. In this case,orthogonality may be achieved by cyclic shift multiplexing and/ordifferent comb assignments. Alternatively, SRS may be transmitted forthe different configured antennas such that transmission alternatesamong (cycles through) the configured antennas in each of theWTRU-specific subframes until deactivation. As an alternative to theWTRU transmitting the SRS for the antennas in sequence, the antenna forwhich the WTRU may transmit SRS may be in accordance with a predefinedpattern. For example, it may be based on the frequency hoppingparameters, (such as in LTE R8). As an alternative to transmitting inevery WTRU-specific subframe, the WTRU may transmit SRS in every NthWTRU-specific subframe.

The above solutions may be extended to the multiple antenna case inwhich each antenna may have an antenna-specific subframe configuration.In this case, given a trigger, the WTRU may transmit SRS for eachantenna (that is configured for SRS) in the next antenna-specificsubframe that is at least four subframes after the triggering subframe n(i.e., n+4 or later) for that antenna and then in each of the next Ns-1antenna-specific subframes for that antenna. If the subframe parametersare the same for all antennas, SRS may be transmitted for all antennasin the same subframe. In this case orthogonality may be achieved bycyclic shift multiplexing and/or different comb assignments. As analternative to transmitting in every antenna-specific subframe, the WTRUmay transmit SRS in every Nth antenna-specific subframe.

The activation/deactivation solution may be extended to the multipleantenna case in which each antenna has an antenna-specific subframeconfiguration. In this case, given a trigger (i.e., activation), theWTRU may transmit SRS for each antenna, (that is configured for SRS), inthe next antenna-specific subframe that is at least four subframes afterthe triggering subframe n (i.e., n+4 or later) for that antenna and thenin each of the next antenna-specific subframes for that antenna untildeactivation. If the subframe parameters are the same for all antennas,SRS may be transmitted for all antennas in the same subframe. In thiscase orthogonality may be achieved by cyclic shift multiplexing and/ordifferent comb assignments. As an alternative to transmitting in everyantenna-specific subframe, the WTRU may transmit SRS in every Nthantenna-specific subframe.

In another solution for handling multiple transmissions, the number ofSRS transmissions to occur as a result of one SRS trigger, Ns, may be aconfiguration parameter provided by the network as part of a modifiedWTRU-specific configuration to be used by WTRUs supporting aperiodicSRS. Alternatively, it may be provided with the trigger. For example, aspart of the DCI format, (e.g., an UL grant), that triggers the SRS.

In another solution for handling multiple transmissions,activation/deactivation may be used such that once SRS transmission isactivated, SRS transmission continues until it is deactivated. Differentmethods of activation/deactivation are defined below. Activation may beviewed as a type of trigger.

In one example method, activation may be a toggle mechanism using aspecial DCI format, (e.g., a special UL grant), which may be understoodby the WTRU to be the activation/deactivation. For example, wheneverthis DCI format, (e.g., UL grant), may be received, it is understood bythe WTRU to mean that if aperiodic SRS is inactive, then activate it andif aperiodic SRS is active, then deactivate it.

In another example method, activation may be one explicit bit indicatingactivation or deactivation. This bit may be in a DCI format such as aspecial or modified UL grant. For example, a single bit may be used foractivate/deactivate. One state of the bit may represent activate and theother state may represent deactivate. The first time the bit is receivedin the activate state, the WTRU may interpret it to mean activateaperiodic SRS and begin transmitting SRS, (such as in accordance withany of the solutions relating to handling activation/deactivationdescribed herein). If the bit is received again in the activate state,the WTRU may continue to transmit SRS. If the bit is received in thedeactivate state, the WTRU may stop transmitting SRS.

In the solutions described herein that refer to WTRU-specific subframes,these WTRU-specific subframes may be the same as those currently definedfor LTE R8 for periodic SRS, or they may be SRS transmission subframesthat are specifically defined and configured for aperiodic SRS.

Described herein are methods for handling multiple component carriers(CCs). Aperiodic SRS may be transmitted on the CC associated with the ULgrant containing the SRS trigger. However, in support of schedulingdecisions for future grants, it may be advantageous to the base stationto be able to obtain measurements for a CC different from the one forwhich it provided an UL grant. Therefore methods are described hereinthat, in part, may trigger SRS transmission on more than just the CCassociated with the UL grant. Moreover, since periodic SRS as definedfor LTE R8 may not include support for multiple CCs, the describedmethods, in part, may handle periodic SRS transmissions in the contextof multiple CCs.

In a solution for handling CCs, the WTRU may be configured to transmiton CCs other than the one associated with the UL grant when the UL grantis used as a trigger. For example, the WTRU may be configured totransmit SRS on all active UL CCs. In another example, the WTRU may beconfigured to transmit SRS on all UL CCs. The network may send RRCsignaling to the WTRU to configure on which of the CCs to transmit SRS.The options may include the CC associated with the UL grant, all UL CCs,and all active UL CCs. Alternatively, physical layer signaling such asthe DCI format that is (or includes) the trigger may include thisconfiguration. Alternatively, it may be predefined as to whether theWTRU should transmit SRS on all UL CCs or all active UL CCs. Thetrigger, (e.g., UL grant or other DCI format), or higher layer signalingmay designate that transmission of SRS may be cycled through the CCsconfigured for SRS transmission. In that case, the WTRU may transmit SRSfor the configured CCs, cycling through the CCs, in the next subframesthat satisfy the defined trigger to transmission subframe relationship.

In another solution for handling CCs, for the case in which there isPUSCH or PUCCH data in the subframe in which SRS may be transmitted, theWTRU may transmit SRS on the same CC(s) as the CC(s) being used for thePUSCH or PUCCH transmission.

In another solution for handling CCs, for the case in which there is noPUSCH and no PUCCH data in the subframe in which the SRS will betransmitted, the WTRU may transmit SRS on the same CC(s) as the CC(s)last used for PUSCH transmission. Alternatively, for the case in whichthere is no PUSCH and no PUCCH data in the subframe in which the SRSwill be transmitted, the WTRU may transmit SRS on the same CC(s) as theCC(s) last used for either PUSCH and/or PUCCH transmission.

Described herein are methods for the specification of the bandwidth (BW)for the SRS transmission. SRS transmission in LTE R10 or LTE-A may bemore flexible in locations/bandwidth than LTE R8 periodic SRS. Themethods described herein may specify the locations/bandwidth. For thecase of an UL grant being used for the aperiodic SRS trigger, the WTRUmay interpret the resource allocation in the UL grant to be thelocation/bandwidth in which the WTRU should transmit SRS. For example,the WTRU may obtain the resource blocks (RBs) in which it shouldtransmit SRS using the resource allocation fields in the DCI format. TheWTRU may interpret the UL grant to mean transmit SRS in the subframe,(per the defined relationship of trigger to subframe), in the lastsymbol within the physical resource blocks (PRBs) assigned in theresource allocation of that UL grant. Within the PRBs, the transmissionmay still be a comb, (similar to LTE R8), and an assigned cyclic shiftmay be used for each SRS transmission. One comb and one cyclic shift maybe used per SRS transmission. Transmission on multiple antennas may beconsidered multiple SRS transmissions. The WTRU may interpret thesepossibilities and perform the SRS transmission accordingly.

Described herein are methods for handling periodic SRS. For periodicSRS, the WTRU may transmit SRS in WTRU-specific subframes as defined forLTE R8. The WTRU may transmit SRS on one antenna or two antennas asdefined for LTE R8 even if the WTRU has more than two antennas.Alternatively, the WTRU may transmit on all antennas in sequence, i.e.,cycle through the antennas. The antenna on which to transmit may bedetermined by the subframe number of the WTRU-specific subframe on whichthe transmission will be made. It may be configurable, such as by RRCsignaling from the network, as to whether to follow the LTE R8 rules orto cycle through all the antennas. As an alternative to the WTRUtransmitting the SRS for the antennas in sequence, the antenna for whichthe WTRU transmits SRS may be in accordance with a predefined pattern.For example, it may be based on the frequency hopping parameters, (suchas in LTE R8).

In another solution for periodic SRS, in a WTRU-specific subframe, theWTRU may transmit SRS on all active UL CCs, or, alternatively, on all ULCCs. It may be configurable, such as by RRC signaling from the network,as to whether to transmit SRS on all UL CCs or all active UL CCs.Alternatively, whether the WTRU transmits SRS on all active UL CCs, or,alternatively, on all UL CCs may be based on a predefined rule.

In another solution, for the case in which there is PUSCH or PUCCH datain the subframe in which SRS will be transmitted, the WTRU may transmitSRS on the same CC(s) as the CC(s) being used for the PUSCH or PUCCHtransmission.

In another solution, for the case in which there is no PUSCH and noPUCCH data in the subframe in which the SRS will be transmitted, theWTRU may transmit SRS on the same CC(s) as the CC(s) last used for PUSCHtransmission. Alternatively, for the case in which there is no PUSCH andno PUCCH data in the subframe in which the SRS will be transmitted, theWTRU may transmit SRS on the same CC(s) as the CC(s) last used foreither PUSCH and/or PUCCH transmission.

Described herein are solutions that relate to when to transmit SRS inresponse to a trigger. In one solution, given a trigger in subframe n,(such as an UL grant), the WTRU may transmit SRS in the subframe that isfour subframes after the triggering subframe n (i.e., subframe n+4) ifand only if that subframe is a WTRU-specific subframe. For example forFDD, an SRS trigger in subframe ‘n’ results in an SRS transmission insubframe n+4 if and only if subframe n+4 satisfies the WTRU-specific SRSsubframe offset and SRS periodicity configuration parameters(10·n_(f)+k_(SRS)−T_(offset))modT_(SRS)=0.

In another solution, given a trigger in subframe n, (such as an ULgrant), the WTRU may transmit SRS in the subframe that is four subframesafter the triggering subframe n (i.e., subframe n+4) if and only if thatsubframe is an antenna-specific subframe.

Described herein are methods for extending the LTE R8/9 antennainformation elements to support multiple antennas. Antenna informationelements that may be used in LTE R8/9 RRC signaling are shown in Table13.

TABLE 13 -- ASN1START AntennaInfoCommon ::= SEQUENCE { antennaPortsCount  ENUMERATED {an1, an2, an4, spare1} }AntennaInfoDedicated ::= SEQUENCE {  transmissionMode  ENUMERATED {  tm1, tm2, tm3, tm4, tm5, tm6,   tm7, tm8-v9x0}, codebookSubsetRestriction  CHOICE {   n2TxAntenna-tm3   BIT STRING(SIZE (2)),   n4TxAntenna-tm3   BIT STRING (SIZE (4)),   n2TxAntenna-tm4  BIT STRING (SIZE (6)),   n4TxAntenna-tm4   BIT STRING (SIZE (64)),  n2TxAntenna-tm5   BIT STRING (SIZE (4)),   n4TxAntenna-tm5   BITSTRING (SIZE (16)),   n2TxAntenna-tm6   BIT STRING (SIZE (4)),  n4TxAntenna-tm6   BIT STRING (SIZE (16))  }   OPTIONAL,             -- Cond TM ue-TransmitAntennaSelection  CHOICE{   release NULL,   setup  ENUMERATED {closedLoop, openLoop}  } }AntennaInfoDedicated-v9x0 ::= SEQUENCE {  codebookSubsetRestriction-v9x0CHOICE {   n2TxAntenna-tm8-r9   BIT STRING (SIZE (6)),  n4TxAntenna-tm8-r9   BIT STRING (SIZE (32))  }   OPTIONAL             -- Cond PMIRI } -- ASN1STOP

In LTE R8/9, a WTRU with two antennas may only transmit using oneantenna at a time. The IE ue-TransmitAntennaSelection may be used toconfigure how the WTRU determines from which antenna port to transmit.In one solution for LTE R10, the antenna selection parameter may be usedin a manner similar to that used in LTE R8/9, but may be extended tosupport LTE-A scenarios, such as supporting more than two antennas. Inanother solution, the antenna selection parameter may be used to specifywhether the WTRU may use the parallel, (multiple antennas in onesubframe), or series, (one antenna in each subframe), transmissionscheme for SRS. For example, one of the two LTE R8/9 values may beredefined to mean parallel and the other may be redefined to meanseries.

Described herein are power related solutions for SRS on multiple CCs.The power setting for SRS transmission, (in aperiodic SRS transmissionand/or periodic SRS transmission) in subframe i on CC c may be expressedas:

P _(SRS)(i,c)=min{P _(CMAX)(c),P _(SRS_offset)(c)+10 log 10(M _(SRS),c)+P _(O_PUSCH)(j,c)+α(j,c)·PL+f(i,c)}   Equation 3

If the sum of the SRS power levels on multiple CCs would exceed the WTRUmaximum configured transmit power, Pcmax, alternatively Ppowerclass, theWTRU may do one of the following where in all of the solutions, Pcmaxmay be replaced by the maximum power of the WTRU's powerclass,Ppowerclass. In one solution, the WTRU may reduce the SRS power equally,(or proportional to SRS BW), on each CC to comply with the maximum powerlimitation, i.e.,

${{\sum\limits_{c}{P_{SRS}\left( {i,c} \right)}} \leq P_{CMAX}}.$

In another solution, the WTRU may scale the SRS power on each CC such as

${\sum\limits_{c}{w_{c} \cdot {P_{SRS}\left( {i,c} \right)}}} \leq P_{CMAX}$

where w_(c) is a scaling factor for SRS on CC c subject to

${{\sum\limits_{c}w_{c}} = 1}.$

For example, w_(c) may be configured by higher layers or the basestation.

In another solution, the WTRU may drop the SRS transmission on some ofthe CCs such that

${\sum\limits_{c^{\prime} \in {\{{{not}\mspace{14mu} {dropped}\mspace{14mu} {CCs}}\}}}{P_{SRS}\left( {i,c^{\prime}} \right)}} \leq {P_{CMAX}.}$

Which CC(s) may be dropped may be configured or pre-defined, (forexample, based on the priority of the CCs). For example, the WTRU maydrop the CC(s) on which there is no PUSCH and/or no PUCCH.Alternatively, the WTRU may autonomously determine which CC(s) needs tobe dropped. For example, the WTRU may drop the CC(s) on which there isno PUSCH and/or no PUCCH.

In another solution, the WTRU may transmit SRS only on the CC associatedwith the UL grant. That is, the WTRU may drop SRS transmission all theother CCs.

Described herein are WTRU procedures for handling SRS and otherchannel(s) transmissions in carrier aggregation (CA). In LTE R8/9, whena WTRU's SRS transmission and other physical channel transmission happento coincide in the same (SRS) subframe, there are rules for the WTRU toavoid simultaneously transmitting SRS and other channel(s) in the lastOFDM symbol in the same subframe. This maintains the single carrierproperty, such that when both SRS and PUSCH of a WTRU are scheduled tobe transmitted in the same subframe, (which may occur in an SRScell-specific subframe), the last OFDM symbol of the subframe may not beused for PUSCH transmission by the WTRU. If SRS and PUCCH format 2/2a/2btransmissions of a WTRU happen to coincide in the same subframe, theWTRU may drop SRS. When SRS transmission and PUCCH transmission carryingACK/NACK and/or positive SR of a WTRU happen to coincide in the samesubframe, and the parameter ackNackSRS-SimultaneousTransmission isFALSE, the WTRU may drop SRS. Otherwise, (i.e.,ackNackSRS-SimultaneousTransmission=“TRUE”), the WTRU may transmit SRSand PUCCH with the shortened format.

In addition, if PUSCH of a WTRU is scheduled to be transmitted in an SRScell specific subframe and SRS transmission is not scheduled in thatsubframe for that WTRU, the WTRU may still not transmit PUSCH in thelast OFDM symbol of the subframe if the BW of the PUSCH even partiallyoverlaps the BW of the SRS configured in the cell, (this is to avoidinterference with an SRS that may be transmitted by another WTRU in thecell). If there is no overlap, the WTRU may transmit the PUSCH in thelast OFDM symbol.

In LTE R10, PUCCH may be transmitted only on the primary cell (PCell) bythe WTRU and PUSCH may be scheduled on one or more activated servingcell(s). In addition, the WTRU may be configured to transmit SRS on aper serving cell (i.e., CC) basis. If in a given subframe, the WTRU maytransmit SRS on one or more serving cells and PUSCH on one or moreserving cells and PUCCH on one or more serving cells, (currently allowedonly on the primary serving cell), there may be multiple transmissionsin the last OFDM symbol which may result in the WTRU exceeding maximumpower in that symbol. The methods described herein, in part, avoid orreduce the occurrence of the maximum power condition and/or address themaximum power condition.

Described herein are methods for SRS(s) and PUSCH(s) transmissions.There may be a case where the WTRU is scheduled to transmit PUSCH(s) onone or more serving cell(s) in a subframe and is also scheduled totransmit SRS(s) on one or more serving cell(s) in that subframe and/orthe subframe is an SRS cell specific subframe for one or more servingcells for which the WTRU is not scheduled to transmit SRS. For example,the WTRU may be scheduled, (e.g., via UL grant), to transmit PUSCH onthe primary cell, (or a secondary cell), and may be scheduled, (e.g.,via periodic scheduling or aperiodic trigger), to transmit SRS(s) in thesame subframe on a serving cell, (the primary cell or a secondary cell).The methods or solutions described herein, in part, handle thesescheduling conflicts. In these examples, two cells are used forillustration purposes, Cell1 and Cell2, where Cell1 and Cell2 may eachbe any one of the serving cells (primary or secondary); the solutionsmay be applied to any number of cells.

In a solution, when a WTRU may be scheduled to transmit PUSCH on aserving cell, (for example Cell 1), in a serving cell specific SRSsubframe of one or more serving cells, and the WTRU may be scheduled totransmit SRS on at least one of the serving cells in that subframe, thenthe WTRU may not transmit PUSCH in the last OFDM symbol of the subframeon Cell 1.

In another solution, when a WTRU may be scheduled to transmit PUSCH on aserving cell, (for example Cell 1), in a serving cell specific SRSsubframe of one or more serving cells, and the WTRU is not scheduled totransmit SRS on any serving cell in that subframe, then the WTRU may nottransmit PUSCH in the last OFDM symbol of the subframe on Cell 1 if thePUSCH resource allocation, (for Cell 1), even partially overlaps withthe SRS bandwidth configuration for any of the serving cells for whichthe subframe is a SRS cell specific subframe.

In another solution, the WTRU may follow one or more rules for one ormore of the cases described for this solution. In a first case, PUSCH ison Cell 1 and SRS is on Cell 1. When the WTRU is scheduled to transmitPUSCH on a serving cell, (for example Cell 1), in a serving cellspecific SRS subframe of that same cell and the WTRU is also scheduledto transmit SRS for that serving cell (Cell 1) in that subframe, one ofthe following rules may be used. In accordance with a first rule, theremay be no change to the LTE R8/9 rule and as such the WTRU does nottransmit PUSCH in the last OFDM symbol of the subframe on Cell 1.

In accordance with a second rule, the LTE R8 rule may be applied with amodification in that the WTRU may not transmit PUSCH in the last OFDMsymbol of the subframe on Cell 1 if the PUSCH resource allocation, (forCell 1), even partially overlaps with the SRS bandwidth configurationfor Cell 1. Otherwise, the WTRU may transmit both PUSCH and SRS in thesame subframe where the last OFDM symbol may also be used for the PUSCHtransmission. In this case a maximum power procedure may be needed tohandle simultaneous SRS and PUSCH transmissions as described herein.

In a second case, PUSCH is on Cell 1, SRS is on Cell 2, and the subframeto transmit in is not an SRS cell-specific subframe on Cell 1. When theWTRU is scheduled to transmit PUSCH on a serving cell, (for example Cell1), in a non-SRS cell specific subframe, (i.e., not a serving cellspecific SRS subframe of the same cell) and the WTRU is also scheduledto transmit SRS for another serving cell, (for example Cell 2), in thatsubframe, one or more of the following rules may be used. In accordancewith a first rule, rule 1, the WTRU may not transmit PUSCH in the lastOFDM symbol on Cell 1 to avoid potential power issues. In accordancewith rule two, the WTRU may prepare to transmit PUSCH in Cell 1 andaddresses a maximum power issue in the last OFDM symbol if it occurs ordrops SRS, (one or more if there are multiple SRS). In accordance withrule three, the WTRU may prepare to transmit PUSCH in Cell 1 and ifthere are any maximum power issues in the last symbol, the WTRU may nottransmit PUSCH in the last OFDM symbol on Cell 1, (in this case the basestation may need to determine what the WTRU did for PUSCH by, forexample, blind detection).

In a third case, PUSCH is on Cell 1, the subframe to transmit in is aSRS cell specific subframe for Cell 1, but no SRS transmission isscheduled for this WTRU. When the WTRU is scheduled to transmit PUSCH ona serving cell, (for example Cell 1), in a serving cell specific SRSsubframe of that same cell, but is not scheduled to transmit SRS forthat serving cell (Cell 1) in that subframe, one or more of thefollowing rules may be used. In accordance with a first rule, the LTER8/9 rule, described as follows, may be applied. The WTRU does nottransmit PUSCH in the last OFDM symbol of the subframe on Cell 1 if thePUSCH resource allocation (for Cell 1) even partially overlaps with theSRS bandwidth configuration for Cell 1. Otherwise, the WTRU may transmitPUSCH normally, (including in the last OFDM symbol) as in LTE R8.

In a fourth case, PUSCH is on Cell 1, the subframe to transmit in is anSRS cell-specific subframe for Cell 2, but not for Cell 1, and no SRStransmission is scheduled. When the WTRU is scheduled to transmit PUSCHon a serving cell, (for example Cell 1), in a non-SRS cell specificsubframe, (i.e., not a serving cell specific SRS subframe of the samecell) and the same subframe is a serving cell specific SRS subframe ofanother serving cell, (for example Cell 2), but no SRS transmissionoccurs (on Cell 2) in the subframe for this WTRU, then, there is nomaximum power issue in this case due to combined PUSCH and SRS.Therefore the WTRU may transmit PUSCH normally.

In a fifth case, PUSCH is on Cell 1, the subframe is an SRS cellspecific subframe for both Cell 1 and Cell 2, SRS transmission isscheduled in this subframe for Cell 2, but not Cell 1. When the WTRU isscheduled to transmit PUSCH on a serving cell, (for example Cell 1), ina serving cell specific SRS subframe of that same cell, but is notscheduled to transmit SRS for that serving cell (Cell 1) in thatsubframe, while the same subframe is a serving cell specific SRSsubframe of another serving cell, (for example Cell 2), where this WTRUtransmits SRS on that cell (Cell 2), one or more of the following rulesmay be used. In accordance with a first rule, the WTRU may not transmitPUSCH in the last OFDM symbol of the subframe on Cell 1 if the PUSCHresource allocation, (for Cell 1), even partially overlaps with the SRSbandwidth configuration for Cell 1. Otherwise, the WTRU may transmitPUSCH normally, (including in the last OFDM symbol), on Cell 1. In thiscase, a maximum power procedure may be needed to handle simultaneous SRS(on Cell 2) and PUSCH transmissions (on Cell 1) as described herein. Inaccordance with a second rule, to avoid a possible power issue, the WTRUmay not transmit PUSCH in the last OFDM symbol of the subframe on Cell1.

FIG. 9 is a flowchart 900 illustrating some of the example methods orsolutions described herein for handling potential conflicts betweenPUSCH and SRS transmissions. Initially, a WTRU may have a PUSCHtransmission scheduled in a subframe for a serving cell, for exampleCell 1 (905). The WTRU determines if the subframe is an SRS cellspecific subframe for Cell 1 (910). If the subframe is an SRS cellspecific subframe, then WTRU determines if SRS transmission is scheduledin this subframe for Cell 1 (915). If SRS and PUSCH are scheduled fortransmission in the same subframe for Cell 1, then the WTRU does nottransmit PUSCH in the last OFDM symbol of the subframe for Cell 1 (920).If an SRS transmission is not scheduled in the subframe for Cell 1, theWTRU then determines if the PUSCH BW overlaps, even partially, with theconfigured SRS BW for Cell 1 (925). If the PUSCH BW and SRS BW at leastpartially overlap, then the WTRU does not transmit PUSCH in the lastOFDM symbol of the subframe for Cell 1 (920).

If the subframe is an SRS cell specific subframe for Cell 1 but an SRStransmission is not scheduled in the subframe and there is no overlapbetween the PUSCH BW and the SRS BW, or the subframe is not an SRS cellspecific subframe for Cell 1, then the WTRU determines if the subframeis a SRS cell specific subframe for any other serving cell (930). If thesubframe is not an SRS cell specific subframe for Cell 1 or any otherserving cell, then the WTRU may transmit the PUSCH normally in Cell 1(935). That is, the PUSCH transmission may occur in the last OFDM symbolfor the subframe.

If the subframe is an SRS cell specific subframe for another servingcell, the WTRU then determines if an SRS transmission is scheduled inany of those serving cells (940). If an SRS transmission is notscheduled in any of those serving cells, then the WTRU may transmit thePUSCH normally in Cell 1 (935). If an SRS transmission is scheduled foranother serving cell, then the WTRU may have two alternative approaches.In a first option (945), the WTRU may not transmit PUSCH in the lastOFDM symbol of the subframe for Cell 1 (920). In a second option (950),the WTRU may prepare to transmit PUSCH normally including in the lastOFDM symbol of the subframe (955). The WTRU may then determine whetherthe power needed to transmit will exceed the maximum transmit power inthe last OFDM symbol (960). If the power level will not exceed themaximum power, then the WTRU may transmit the PUSCH normally in Cell 1(935). That is, the PUSCH transmission may occur in the last OFDM symbolfor the subframe. If the power level required will exceed the maximumtransmit power in the last OFDM symbol, then the WTRU may adjust powerlevels and/or the channels to fall below the maximum transmit power inthe last OFDM symbol and then transmit in the subframe (965).

Described herein are methods for handling SRS(s) and PUCCHtransmissions. In these methods, two cells are used for illustrationpurposes, Cell1 and Cell2, where Cell1 and Cell2 may each be any one ofthe serving cells (primary or secondary); the solutions may be appliedto any number of cells.

In a first case, when the WTRU transmits PUCCH on the primary cell, (forexample Cell 1), in a serving cell specific SRS subframe of that samecell, and the WTRU is also scheduled to transmit SRS for Cell 1, (e.g.,primary cell), in that subframe, one or more of the following rules maybe used.

In accordance with a first rule, the LTE R8 rules may be applied withrespect to transmission, priority, shortened PUCCH format 1/1a/1b, PUCCHformat 2/2a/2b, and a shortened PUCCH format 3 may be added. Forexample, if PUCCH format 2/2a/2b transmission takes place in the samesubframe, the WTRU may drop SRS, (that is, PUCCH format 2/2a/2b haspriority over SRS). Also, if PUCCH transmission, (with format 1/1a/1b orformat 3), carrying acknowledgement/negative acknowledgement (ACK/NACK)and/or positive scheduling request (SR) occurs in the same subframe andif the parameter ackNackSRS-SimultaneousTransmission is FALSE, the WTRUmay drop SRS. Otherwise, (i.e.,ackNackSRS-SimultaneousTransmission=“TRUE”), the WTRU may transmit SRSand PUCCH with the shortened format where with the shortened format, thelast OFDM symbol of the subframe, (which corresponds to the SRSlocation) may be punctured for the PUCCH transmission.

In accordance with a second rule, the WTRU may simultaneously transmitSRS and PUCCH format 3 using a shortened format for PUCCH format 3 whensimultaneous ACK/NACK and SRS are allowed. The use of the shortenedformat for PUCCH format 3, however, may be limited to a small number ofACK/NACK bits, for example, up to N bits, (e.g., N=4) such that it maynot be usable in some cases. For example, if the number of ACK/NACK bitsto be transmitted is smaller than or equal to N, and if the parameterackNackSRS-SimultaneousTransmission is TRUE, (in a serving cell specificsubframe), the WTRU may transmit ACK/NACK (and SR) using the shortenedPUCCH format. However, if the number of ACK/NACK bits to be transmittedis greater than N or the parameter ackNackSRS-SimultaneousTransmissionis FALSE, then the WTRU may drop SRS and transmit the PUCCH with normalformat 3 in the subframe. Alternatively, the WTRU may not transmit SRSwhenever SRS and PUCCH format 3 transmissions occur in the samesubframe. In this case the normal PUCCH format 3 would be used.

In accordance with a third rule, the WTRU may be allowed to transmitPUCCH, (with normal PUCCH format, i.e., without the shortened format),and SRS in the last symbol of that subframe, and the potential maximumpower issues may be handled using, for example, the scaling rulesdescribed herein.

For a second case, when the WTRU may transmit PUCCH on a serving cell,e.g., the primary cell, (for example Cell 1), in a non-SRS cell specificsubframe, (i.e., not a serving cell specific SRS subframe of the samecell) and the WTRU may also be scheduled to transmit SRS for anotherserving cell, (for example Cell 2), in that subframe, one or more of thefollowing rules may be used. In accordance with a first rule, the WTRUmay not transmit PUCCH in last OFDM symbol on Cell 1, (i.e., using theshortened PUCCH format, for example, for PUCCH format 1/1a/1b and PUCCHformat 3) to avoid a potential transmit power issue. In accordance witha second rule, the WTRU may prepare to transmit PUCCH in Cell 1 andaddresses the maximum power issue in the last OFDM symbol if it occursusing, for example, the scaling rules described herein.

In accordance with a third rule, the WTRU may prepare to transmit PUCCHin Cell 1 and if there are any maximum power issues in the last symbol,(for example, Ppucch+Psrs>Pmax), the WTRU may not transmit PUCCH in thelast symbol of the subframe on Cell 1, (for example using the shortenedPUCCH format). In this case, the base station may need to determine whatthe WTRU did by, for example, using blind detection.

For a third case, when the WTRU may transmit PUCCH on a serving cell,e.g., the primary cell, (for example Cell 1), in a serving cell specificSRS subframe of that same cell, but the WTRU does not transmit SRS forthat serving cell, e.g., primary cell (Cell 1) in that subframe, thenthe following rule may be used. In accordance with the rule, the WTRUmay transmit the PUCCH without any constraint, (except for maximum CC(Cell) power limit).

For a fourth case, when the WTRU may transmit PUCCH on a serving cell,e.g., the primary cell, (for example Cell 1), in a non-SRS cell specificsubframe, (i.e., not a serving cell specific SRS subframe of the samecell), and the same subframe is a serving cell specific SRS subframe ofanother serving cell, (for example Cell 2), but the WTRU does nottransmit SRS on that cell (on Cell 2) in the subframe for this WTRU,there is no maximum power issue in this case due to combined PUCCH andSRS and the WTRU may transmit PUCCH normally.

For a fifth case, when the WTRU transmits PUCCH on a serving cell, e.g.,the primary cell, (for example Cell 1), in a serving cell specific SRSsubframe of that same cell, but the WTRU does not transmit SRS for thatserving cell (Cell 1) in that subframe, while the same subframe is aserving cell specific SRS subframe of another serving cell, (for exampleCell 2), where this WTRU transmits SRS on Cell 2, one or more of thefollowing rules may be used. In accordance with a first rule, the WTRUmay not transmit PUCCH in last OFDM symbol on Cell 1, (i.e., using theshortened PUCCH format, for example, for PUCCH format 1/1a/1b and PUCCHformat 3) to avoid a potential transmit power issue.

In accordance with a second rule, the WTRU may prepare to transmit PUCCHin Cell 1 and addresses the maximum power issue in the last OFDM symbolif it occurs using, for example, the scaling rules described herein. Inaccordance with a third rule, the WTRU may prepare to transmit PUCCH inCell 1 and if there are any maximum power issues in the last symbol,(for example, Ppucch (on Cell1)+Psrs (on Cell2)>Pmax), the WTRU may nottransmit PUCCH in the last symbol of the subframe on Cell 1, (e.g.,using the shortened PUCCH format, for example, for PUCCH format 1/1a/1band PUCCH format 3).

FIG. 10 is a flowchart 1000 illustrating some of the example methods orsolutions described herein for handling potential conflicts betweenPUCCH and SRS transmissions. Initially, a WTRU may have a PUCCHtransmission scheduled in a subframe for a serving cell, for exampleCell 1 (1005). The WTRU determines if the subframe is an SRS cellspecific subframe for Cell 1 (1010). If the subframe is an SRS cellspecific subframe, then WTRU determines if SRS transmission is scheduledin this subframe for Cell 1 (1015). If an SRS transmission is notscheduled in the subframe for Cell 1, then the WTRU may transmit thePUCCH in Cell 1 (1020).

If SRS and PUCCH are scheduled for transmission in the same subframe forCell 1, then the WTRU may have two options. In a first option (1025),the WTRU may apply the LTE R8 rules for transmission of SRS and PUCCH(1030). In a second option (1035), the WTRU may perform power levelchecks before any transmission as detailed herein below.

If the subframe is not an SRS cell specific subframe for Cell 1, thenthe WTRU determines if the subframe is a SRS cell specific subframe forany other serving cell (1040). If the subframe is not an SRS cellspecific subframe for Cell 1 or any other serving cell, then the WTRUmay transmit the PUCCH normally in Cell 1 (1045).

If the subframe is an SRS cell specific subframe for another servingcell, the WTRU then determines if an SRS transmission is scheduled inany of those serving cells (1050). If an SRS transmission is notscheduled in any of the other serving cells, then the WTRU may transmitthe PUCCH normally in Cell 1 (1045). If an SRS transmission is scheduledthen the WTRU may have two options. In a first option (1055), the WTRUmay apply the LTE R8 rules for PUCCH and SRS (1030). In a second option(1060), (which is also the second option 1035 from above), the WTRU mayprepare to transmit PUCCH including in the last OFDM symbol of thesubframe (1065). The WTRU may then determine whether the power needed totransmit will exceed the maximum transmit power in the last OFDM symbol(1070). If the power level will not exceed the maximum transmit power,then the WTRU may transmit the PUCCH normally in Cell 1 (1045). If thepower level required will exceed the maximum transmit power in the lastOFDM symbol, then the WTRU may adjust power levels and/or the channelsto fall below the maximum transmit power in the last OFDM symbol andthen transmit in the subframe (1075).

Described herein are methods for handling SRS(s) and PUSCH(s)/PUCCHtransmissions. If the WTRU is configured to simultaneously transmitPUSCH and PUCCH on either the same cell, (e.g., primary cell) ordifferent cells, (i.e., PUCCH on one cell, e.g., the primary cell andPUSCH on another cell, e.g., a secondary cell), one or a combination ofthe method(s)/solution(s)/alternative(s)/rule(s) described above may beapplied for each channel. The following are further illustrative casesand rules for SRS and simultaneous PUSCH and PUCCH transmission. Inthese examples, two cells are used for illustration purposes, Cell1 andCell2, where Cell1 and Cell2 may each be any one of the serving cells(primary or secondary); the solutions may be applied to any number ofcells.

In a first case, when the WTRU may transmit both PUSCH and PUCCH on aserving cell, e.g., the primary cell, (for example Cell 1), in a servingcell specific SRS subframe of that same cell and the WTRU may also bescheduled to transmit SRS for the primary (Cell 1) in that subframe,then the following rule may be used. In accordance with the rule, theLTE R8 rule may be applied for the PUSCH transmission. For PUCCHtransmission, one or a combination of the rules described above may beapplied.

For a second case, when the WTRU may transmit PUCCH on a serving cell,e.g., the primary cell, (for example Cell 1), in a serving cell specificSRS subframe of that same cell, and the WTRU may be scheduled totransmit PUSCH on another serving cell, (for example Cell 2), in thesame subframe, (but it is not a serving cell specific SRS subframe ofthe same cell, Cell 2), and the WTRU may also be scheduled to transmitSRS for (Cell 1) in the same subframe, then one or a combination of therules described above maybe applied for both PUCCH and PUSCH.

For a third case, when the WTRU may transmit PUCCH on a serving cell,e.g., the primary cell, (for example Cell 1), in a non-SRS cell specificsubframe, (i.e., not a serving cell specific SRS subframe of the samecell), and the WTRU may be scheduled to transmit PUSCH on anotherserving cell, (for example Cell 2), in that subframe, (which is aserving cell specific SRS subframe of the same cell, Cell 2), and theWTRU may also be scheduled to transmit SRS for Cell 2 in the samesubframe, then one or a combination of the rules described above may beapplied for both PUCCH and PUSCH.

For a fourth case, when the WTRU may transmit both PUSCH and PUCCH on aserving cell, e.g., the primary cell, (for example Cell 1), in a servingcell specific SRS subframe of that same cell while the same subframe isa serving cell specific SRS subframe of another serving cell, (forexample Cell 2), where this WTRU may transmit SRS on Cell 2, then one ora combination of the rules described above maybe applied for both PUCCHand PUSCH.

In the existing power scaling rules, if simultaneous transmission of allchannels scheduled to be transmitted in a subframe would exceed the WTRUmaximum configured transmit power, P_(CMAX), alternatively the power ofthe WTRU power class, Ppowerclass, the WTRU may scale the channel powersbefore transmission to ensure the maximum is not exceed. The scalingrules are defined such that higher priority channels may not be scaledwhile lower priority channels may be scaled. The current prioritiesdictate a priority order from highest to lowest as PUCCH, PUSCH with(i.e., containing) UCI, PUSCH without UCI. The current rules do notaddress simultaneous transmission of any of these channels with SRS.

Described herein are methods for handling maximum power scaling in caseof simultaneous SRS(s) and SRS(s) transmitted simultaneously withPUSCH(s) and/or PUCCH(s) transmissions. In any of the above cases where,in a given cell in a given subframe in which SRS may be transmitted inthe last OFDM symbol, and in the same cell and/or another cell, anothersignal or channel, i.e., PUCCH, PUSCH, or SRS, may be simultaneouslytransmitted in that same subframe in the last OFDM symbol, the sum ofthe nominal transmit powers of all such channels or signals may exceedthe configured maximum transmit power of the WTRU, alternatively thepower of the WTRU's power class, Ppowerclass. Preventing the WTRU fromtransmitting above the configured maximum transmit power, alternativelyPpowerclass, may be achieved by one or a combination of the followingmethods.

In one example method, the power scaling rules may be applied separatelyfor all but the last OFDM symbol, and then again for the last OFDMsymbol. For the last OFDM symbol, one or more of the followingadditional or modified rules may be used. In accordance with a rule, theSRS may be specified to have its own unique priority amongst thepriorities of the other channel types, for example as shown in Table 14,and then the existing priority-based power scaling may be applied withmodification to include SRS. Periodic SRS and aperiodic SRS may havedifferent priorities.

TABLE 14 SRS > PUCCH > PUSCH with UCI > PUSCH without UCI, or PUCCH >SRS > PUSCH with UCI > PUSCH without UCI, or PUCCH > PUSCH with UCI >SRS > PUSCH without UCI, or PUCCH > PUSCH with UCI > PUSCH without UCI >SRS

In accordance with another rule, SRS may be specified to have the samepriority as one of the other channel types, i.e., PUCCH, PUSCH with UCI,or PUSCH without UCI, and they may be scaled equally with thesame-priority channel type.

In accordance with another rule, if there are multiple SRS transmissionsacross different cells in the same subframe, then the SRSs may be powerscaled equally. Alternatively, when periodic SRS(s) and aperiodic SRS(s)are transmitted in the same subframe, (and maximum power may be exceededin the last OFDM symbol of the subframe), then some (or all) of periodicSRS(s) may be dropped.

In another method, the power scaling rules may be used separately forall but the last OFDM symbol, and then again for the last OFDM symbol,to determine possibly two different weights for each channel or signal,but the smaller of the two weights may be applied for the entiresubframe.

In another method, power scaling may be applied for the entire subframejust once, assuming that the power levels of all channels or signalsthat are present at any time in the subframe are present for the entiresubframe.

In another method, if maximum power may be exceeded in the last OFDMsymbol in a subframe in which SRS is to be transmitted by a WTRU andthere are other channel types to be transmitted in that symbol by theWTRU besides SRS, the WTRU may drop, (i.e., does not transmit), SRS inthat subframe.

In another method, if maximum power may be exceeded in the last OFDMsymbol in a subframe in which periodic SRS is to be transmitted by aWTRU and there are other channel types to be transmitted in that symbolby the WTRU besides SRS, the WTRU may drop, (i.e., does not transmit),SRS in that subframe.

In general, a method for performing uplink sounding reference signals(SRS) transmissions in a multiple antenna wireless transmit/receive unit(WTRU), comprises receiving a WTRU-specific configuration ofWTRU-specific SRS subframes for performing SRS transmissions, receivinga trigger from a base station to transmit SRS for a predetermined numberof antennas, and transmitting the SRS for the predetermined number ofantennas in predetermined WTRU-specific subframes. The method furthercomprises transmitting SRS in each of a predetermined duration ofWTRU-specific SRS subframes starting a predetermined number ofWTRU-specific SRS subframes after a triggering subframe. Thepredetermined number may be 4. The trigger may be a multi-bit indicatorthat provides predetermined SRS transmission parameters to the WTRU. Apredetermined duration may be received in the WTRU-specificconfiguration.

The method further comprises receiving a cyclic shift reference valueand determining a cyclic shift for an antenna based on at least thecyclic shift reference value. The cyclic shift determined for eachantenna provides a maximum distance between cyclic shifts for theantennas transmitting SRS in a same WTRU-specific subframe.Alternatively, the cyclic shift determined for each antenna provideseven distribution between cyclic shifts for the antennas transmittingSRS in a same WTRU-specific subframe.

The method may use at least one of cyclic shift multiplexing ordifferent transmission comb assignments may be used for transmissionfrom multiple antennas in the predetermined WTRU-specific subframe. SRStransmissions from multiple antennas in the predetermined WTRU-specificsubframe may be done in parallel. The predetermined number of antennasmay be less than the number of antennas available on the WTRU. In themethod, the WTRU-specific SRS subframes may be different for periodicSRS transmission and aperiodic SRS transmission.

The method may further comprise determining resource allocation overlapbetween physical uplink shared channel (PUSCH) and the WTRU-specificconfiguration for SRS and foregoing PUSCH transmission in a last symbolof a subframe on a condition of a partial overlap.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A method for performing uplink sounding referencesignal (SRS) transmissions by a wireless transmit/receive unit (WTRU),the method comprising: receiving a WTRU-specific configuration ofWTRU-specific SRS subframes for performing SRS transmissions; receivinga trigger in a subframe to transmit a first SRS; selecting a firstsubframe, wherein the first subframe is a WTRU-specific subframe and thefirst subframe is at least four subframes after the subframe in whichthe trigger is received; determining that a maximum power would beexceeded in a symbol in the selected first subframe; on a condition thattransmission of at least one other SRS would at least partially overlapin the symbol in the selected first subframe, scaling transmissionpowers of the first SRS and the at least one other SRS equally to complywith the maximum power; and transmitting, in accordance with the scaledtransmission powers, the first SRS in the selected subframe and the atleast one other SRS.